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Free-Space Electro-Optic Modulators


  • High Performance Lithium Niobate Amplitude & Phase Modulators
  • SMA RF Modulation Input Connector
  • Broadband DC Coupled or High Q Resonant

EO-PM-NR-C1

EO-AM-NR-C1

EO-GTH5M Application 

EO-PMT

EO-GTH5M

HVA200

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Lithium Niobate Electro-Optic Modulators

Thorlabs free-space electro-optic (EO) amplitude and phase lithium niobate modulators combine our experience with crystal growth and electro-optic materials. Our EO modulators use MgO-doped lithium niobate for high power operation. The modulators have an SMA RF input, which is directly compatible with our HVA200 High Voltage Amplifier (shown below). We offer both broadband DC-coupled and high Q resonant models.

Vpi Bias Voltage vs. Wavelength for EO Modulators
Click to Enlarge

The required half-wave voltage needed to drive the EO modulators
is a function of the wavelength of the optical signal. The curves labeled
Amplitude Modulators and Phase Modulators describe the broadband
(non-resonant) EO Modulators.

Features

  • High Performance in a Compact Package
  • Broadband DC Coupled or High-Q Resonant
  • 2 mm Diameter Clear Aperture
  • MgO-Doped Lithium Niobate Crystal
  • SMA RF Modulation Input Connector
  • DC to 100 MHz
  • Custom OEM Versions Available
*Please note that AM modulators operating in the
-C4 band (400 - 600 nm) should only be used for AC modulation above a few Hz. MgO-doped lithium niobate can be sensitive to light in this wavelength range, displaying a slow negation to an applied DC field. The more intense the light, the faster the DC field is cancelled. Hence, in practice, a DC voltage cannot be used to bias the modulator at the desired operating point. 

DC-Coupled Broadband Modulators

Our broadband EO modulators consist of an EO crystal packaged in a housing optimized for maximum RF performance. The RF drive signal is connected directly to the EO crystal via the SMA RF input. An external RF driver supplies the drive voltage for the desired modulation. The crystal may be modulated from DC up to the frequency limits of the external RF driver. Please see the Specs tab for amplifier requirements. These broadband amplitude and phase modulators are offered with a -C4* (400 - 600 nm), -C1 (600 - 900 nm), -C2 (900 - 1250 nm), or -C3 (1250 - 1650 nm) AR coating. See the Graphs tab for more information on the reflectance of these coatings.

High Q Resonant Modulators

Resonant EO Modulators are operated at a fixed frequency, and Thorlabs' design includes a high-Q resonant circuit. When compared with the voltage required to drive broadband EO modulators, the operating voltage of resonant EO modulators is dramatically reduced. Our resonant amplitude and phase modulators operating at 20 MHz are offered with a -C1 AR coating (600 - 900 nm). See the Graphs tab for more information on the reflectance of this coating. Standard and custom AR coating options are available, as well as versions with user-specified resonance frequencies from 0.1 to 100 MHz. Please contact Tech Support to discuss your application needs. Please see the Specs tab for more information on these modulators.

Driver and Accessories

Any standard laboratory function generator can drive our resonant modulators. Our HVA200 high voltage amplifier, which features a ±200 V output at 100 mA of continuous current, a 1 MHz bandwidth, and low noise (see the presentation below for more details), is ideal for driving our broadband EO modulators, which are non-resonant, when certain operating conditions are met. Generally speaking, EO modulators driven by the HVA200 can fully modulate signals when the required half-wave voltage is ≤200 V. Because of the dependence of the half-wave voltage on the wavelength of the input optical signal (see the above plot), EO modulators driven by the HVA200 may not be able to fully modulate optical signals that fall at the higher end of the modulators' operational wavelength ranges. More information can be found in the following and on the EO Modulator Intro and Lab Facts tabs. 

Our broadband EO phase modulators (EO-PM-NR) produce phase shifts from -180° to +180° when the drive voltage varies from -Vπ to +Vπ. (Please see the EO Modulator Info tab for more information.) As indicated by the above plot, when the HVA200 is used to drive our EO phase modulators, optical signals with wavelengths up to approximately 900 nm can be fully modulated.  

While the EO phase modulators require the entire ±Vπ range to fully modulate an optical signal, broadband EO amplitude modulators (EO-AM-NR) are able to fully modulate an amplitude signal when the drive voltage varies from 0 to either +Vπ or -Vπ. The requirement that the modulating voltage driving EO amplitude modulators include both 0 V and the maximum or minimum half-wave voltage is limiting; half of the amplifier's voltage range is not available for use. This limitation can be overcome by using a quarter-wave plate to provide an optical bias that will make the entire voltage range of the amplifier available to drive the EO amplitude modulators. The Lab Facts tab describes this technique, which doubles the available voltage range of the amplifier. When this technique is not used, the EO amplitude modulators are limited to fully modulating optical signals with wavelengths up to approximately 620 nm when driven by the HVA200 (please see the above plot). When this technique is used, the HVA200 is able to drive the EO-AM-NR-C1 over its entire wavelength range, and HVA200 can drive the EO-AM-NR-C2 to fully modulate the amplitudes of optical signals with wavelengths up to 1000 nm. 

Please contact Tech Support if you require more information about driving the resonant or non-resonant broadband EO modulators. 

Thorlabs also offers a Glan-Thompson Polarizer mounting adapter, as well as an EO modulator mount for integration into our fiberbench collimation hardware (see below).

Modulators

Item # EO Amplitude Modulator
EO-AM-NR
EO Phase Modulator
EO-PM-NR
EO Resonant Modulator
EO-xM-R
Modulator Crystal Lithium Niobate (LiNbO3) Doped with MgO
Wavelength Range
    C1 600 to 900 nm 600 to 900 nm 600 to 900 nm
    C2 900 to 1250 nm 900 to 1250 nm N/Aa
    C3 1250 to 1650 nm 1250 to 1650 nm N/Aa
    C4 400 to 600 nmb 400 to 600 nm N/Aa
Clear Aperture 2 mm Diameter 2 mm Diameter 2 mm Diameter
Input Connector SMA Female SMA Female SMA Female
Resonant Frequency Range Broadband Broadband 20 MHzc
Half Wave Voltage, Vπ
(Click for Plot)
205 V at 633 nm (Typical)
(Click for Graph)
136 V at 633 nm (Typical)
(Click for Graph)
15 V at 633 nmd (Typical)
(Click for Graph)
Extinction Ratio >10 dB NA >10 dB
Input Capacitance/Impedance 14 pF 14 pF 50 Ohms
Max RF Input Power N/A N/A 3 W (35 Vpp)
Max Optical Power Density 2 W/mm2 @ 532 nm,
4 W/mm2 @ 1064 nm
2 W/mm2 @ 532 nm,
4 W/mm2 @ 1064 nm
2 W/mm2 @ 532 nm,
4 W/mm2 @ 1064 nm
  • Other AR coating ranges are available upon request. Contact Tech Support for details.
  • AM modulators operating in the -C4 band (400 - 600 nm) should only be used for AC modulation above a few Hz. Please see the green box in the Overview tab for more details.
  • Resonant frequencies from 0.1 - 100 MHz are available. Contact Tech Support for details.
  • These modulators are typically used for less than half-wave EO modulation at the 20 MHz resonant frequency. Note that driving full depth of modulation at 20 MHz will cause the max RF input power to be exceeded (15 V = 42 Vpp).

Amplifier

Item # HVA200
Physical Features
Input Connector BNC
Output Connector BNC
HV Monitor Connector BNC
Bias Adjustment Digital Encoder
Output Enable Front Panel Push Button
Output HV Indicator Bright LED
Power Switch Rocker Switch
Dimensions 9" x 5" x 12.5"
(228.6 mm x 127 mm x 317.5 mm)
Weight 11.6 lbs
Other Tilting Rubber-Padded Feet
Max Ratings
Max Output Current 100 mA DC
Max Input Voltage Range –10 V to 10 V
Fuse Rating 630 mA @ 115 VAC (5x20 mm SLO-BLO)
400 mA @ 230 VAC (5x20 mm SLO-BLO)
Electrical Characteristics
Max Input Voltage Range –10 V to 10 V
Input Impedance 1 kΩ
Output Voltage –200 V to 200 V
Output Impedance 50 Ω
Slew Rate 400 V/μs
Output Noise 1.5 mV RMS
Voltage Gaina –20 ± 2%
DC Bias Adjust –200 V to 200 V
HV Monitor to Output Ratio
    With Input Impedance of 50 Ω 40:1 (Vout/40 ± 6%)
    With Input Impedance of >10 kΩ 20:1 (Vout/20 ± 6%)
AC Power 115 V/230 V, 50-60 Hz, 70 VA
  • NOTE: The voltage gain is inverting to preserve the high slew rate of the output amplifier (i.e., a -1 V input results in +20 V output).

These plots show the reflectance of each of our four dielectric coatings for a typical coating run. The shaded region in each graph denotes the spectral range over which the coating is highly transmissive.

Electro-Optic Amplitude Modulator
Click to Enlarge

Figure 2: Electro-Optic Amplitude Modulator
Electro optic phase modulator
Click to Enlarge

Figure 1: Electro-Optic Phase Modulator
EO Phase Modulator Output vs. Bias Voltage
Click to Enlarge

Figure 3: EO Phase Modulator Output as a Function of Applied Voltage (Listed in Terms of Vπ)
The X marks on the curve correspond to the phase shifts listed in the table above the graph.
EO Amplitude Modulator Output as a Function of Bias Voltage
Click to Enlarge

Figure 4: EO Amplitude Modulator Output as a Function of Applied Voltage (Listed in Terms of Vπ)
The X marks on the curve correspond to conditions in the table columns.

Introduction to EO Modulators

Electro-optic (EO) modulators are designed to modulate the phase or intensity (amplitude) of electromagnetic radiation (light) propagating through them. They are used in the Q-switching and mode locking of lasers, the generation of optical pulses, side-band generation, and other applications. EO modulators employ the Pockels effect, which is a linear (to first order) electro-optic phenomenon in which the induced birefringence of certain crystals is proportional to the amplitude of the electric field (voltage) applied across the crystal. Birefringent crystals exhibit one refractive index (n||) for light polarized parallel to the optic axis of the crystal and a different refractive index (n) for light polarized perpendicular to the optic axis. For the crystals used in EO modulators, the optic axis is parallel to the direction of the applied electric field.

Generally speaking, the optical path length (OPL) through a medium is the product of the geometrical length of the path through a medium and the refractive index (nr) of the medium. The refractive index of, and therefore the OPL through, a birefringent crystal is determined by the polarization of the light referenced to the optic axis of the crystal. The OPL through a medium is directly related to the phase accumulated by light travelling through it. When the Pockels effect applies, it is possible to modulate the accumulated phase (phase shift) of the light that propagates through the crystal by modulating the applied voltage. Longer crystals produce larger phase shifts, and the OPL and accumulated phase shift are both functions of the wavelength of the light. EO modulators exploit the changes in the crystal's refractive indices that occur as a response to an applied voltage signal.

EO Phase Modulator

An EO phase modulator applies a voltage-controlled phase shift to the light without affecting its polarization. Figure 1 shows one configuration used to accomplish this: the input light is linearly polarized and aligned with the optic axis of the crystal. As is stated above, the optic axis (parallel to the z-axis in this diagram) is determined by the orientation of the applied electric field. The phase accumulated by the light is a function of the wavelength of the light, the geometric width of the crystal (measured along the y-axis, which is parallel to the direction of propagation), and the refractive index of the optic axis, n||. The modulation of n|| controls the phase modulation of the light; the value of n is not a factor. Figure 3 lists and plots the phase shift as a function of the applied voltage, which is expressed in terms of Vπ. In the plot, the X marks correspond to the values listed in the table above the graph. Vπ is called the half-wave voltage and is defined as the voltage required to shift the output phase by pi radians.

EO Amplitude Modulator

An example of an EO amplitude modulator is shown in Figure 2. In this configuration, the input light is linearly polarized and oriented at a 45° angle to the crystal's optic axis, which is again determined by the direction of the applied electric field. The input light in this case can be equivalently described as the sum of two equal-amplitude and perpendicularly polarized components: one polarized parallel to the optic axis (along z-axis) and one polarized perpendicular to the optic axis (along the x-axis). These two components accumulate phase differently as they propagate through the crystal, which is a consequence of the birefringence of the crystal; the OPL of the component of light polarized parallel to the optic axis is determined by n||, and the OPL of the perpendicularly polarized component is determined by n. As the applied voltage is varied, the difference between the values of the crystal's two refractive indices varies; therefore, the relative phase shift between the two components also varies.

The polarization of the total electromagnetic field (the sum of the components) at the output of the crystal changes as the two components move in and out of phase with one another. The polarization of the light at the output of the crystal is linear when the two components are in or 180° out of phase, circular when they are π/2 radians out of phase, and elliptical otherwise. The amplitude of the light transmitted by the 45° polarizer is a function of the polarization of the light incident on it; when the applied voltage is modulated, the intensity of the output beam is modulated. The light transmitted by the polarizer, and therefore the EO amplitude modulator, is linearly polarized and oriented parallel to the axis of the polarizer.

The data tabulated in Figure 4 shows the effect of the applied voltage on the phase shift and polarization of the total light field at the output of the crystal. The plot shows the amplitude of the light transmitted by the polarizer as a function of the applied voltage over a modulation range of 2Vπ. (The X marks on the curve correspond to the values listed in the above table.) For the configuration shown in Figure 2, the applied voltage signal must vary from 0 V to Vπ (or from -Vπ to 0 V) to fully modulate the amplitude of input light; in order to capture both a maxima and minima, the modulator must pass through 0 V and either +Vπ or -Vπ. This restriction can be modified when a quarter-wave plate is added to the setup (please see the Lab Facts tab).

Driving EO Modulators

EO modulators may be configured so that the voltage is applied in a direction perpendicular to the propagation of light, as shown in Figures 1 and 2, or in a direction parallel to the propagation of light. An advantage of applying the voltage in the transverse orientation, as shown in these figures, is that it is not necessary for the light to travel through the electrodes. This generally results in better light transmission through the modulator and allows electrode materials that are opaque at the operating wavelength to be used. Additionally, in this transverse configuration, the OPL is proportional to the product of the applied field and crystal length.

Variable high voltage supplies, such as a function generator paired with a high voltage amplifier and delivering hundreds of volts, are typically used to drive free-space EO modulators. As shown by the graph included in the Overview tab, the voltage required to drive the EO modulator increases with the wavelength of the light being modulated. Because of this, at longer wavelengths the voltage needed to achieve full modulation of the optical signal can exceed the voltage output range of the high voltage supply. As an example, the HVA200 high voltage amplifier has a range of ±200 V, which is ideal for driving the broadband EO modulators EO-AM-NR and EO-PM-NR when the wavelength of the light is below approximately 610 and 900 nm, respectively. At higher wavelengths, this amplifier does not supply the voltage needed to achieve full-scale modulation of the optical signals. However, when pairing the HVA200 with EO amplitude modulators such as the EO-AM-NR products, it is possible to extend the available voltage range of the HVA200 by placing a quarter-wave plate before the input of the modulator. This procedure is detailed in the Lab Facts tab.

The driving voltage requirements of fiber-coupled EO modulators are often significantly less than those of free-space EO modulators. In many cases, these modulators have half-wave voltages on the order of 4 V, and one challenge of driving them is locating voltage drivers capable of producing a modulating frequency high enough to fulfill the needs of the application. A basic setup built around a function generator and an amplifier that was successfully used to drive a fiber-coupled EO phase modulator to 1 GHz is described here

Electro-optic amplitude modulator no QWP
Click to Enlarge

Figure 1: Electro-Optic Amplitude Modulator Without the Quarter-Wave Plate
Electro-optic amplitude modulator with QWP
Click to Enlarge

Figure 2: Electro-Optic Amplitude Modulator with a Quarter-Wave Plate at the Input

Pairing an EO Amplitude Modulator with a Quarter-Wave Plate to Reduce Drive Voltage Requirements

Variable high voltage supplies, such as a function generator paired with a high voltage amplifier delivering hundreds of volts, are typically used to drive free-space EO modulators. As shown by the graph included in the Overview tab, the voltage required to drive the EO modulator increases with the wavelength of the light being modulated. Because of this, at longer wavelengths the voltage needed to achieve modulation over the full amplitude or phase range can exceed the output voltage range of the high voltage supply. Please see the EO Modulators tab for more information about EO modulators.

Lab Facts Complete Summary

In the case of EO amplitude modulators such as the EO-AM-NR products, placing a quarter-wave plate at the input of the EO amplitude modulator can reduce the maximum voltage necessary to drive the modulator over its full range; when the high voltage supply is the limiting factor, the use of a quarter-wave plate makes available more, or all, of the operational wavelength range of the driven EO amplitude modulator. Figures 1 and 2 show an EO amplitude modulator with and without, respectively, the quarter-wave plate in place. Experiments conducted in our laboratory using the HVA200 high voltage amplifier, which has an output voltage range of ±200 V, and the EO-AM-NR-C1 electro-optic amplitude modulator demonstrate and document this approach. A summary of that work is presented in this tab. Please click on the Lab Facts icon for details.

The experimental setup used the HRS015 HeNe (633 nm) and LP980-SF15 fiber-pigtailed laser (980 nm) as light sources. A linear polarizer (LPVISB100 or LPNIR100) placed after the source ensured the polarization of the input light was at a 45° angle to the optic axis of the EO-AM-NR-C1 electro-optic amplitude modulator. A second linear polarizer placed at the output of the modulator was aligned parallel to the first. The HVA200, which was used to amplify the 100 kHz triangle wave output by a function generator, produced the variable voltage signal (±200 V maximum) driving the EO amplitude modulator. A triangle waveform was chosen to drive the EO amplitude modulator so that the light transmitted by the modulator would be sinusoidally modulated. Data were taken with and without a quarter-wave plate (WPMQ05M-633 or WPMQ05M-980) placed in front of the EO amplitude modulator. When used, the quarter-wave plate was oriented with its axis parallel to the optic axis of the crystal. (Figure 2 shows the placement and orientation of the quarter-wave plate with respect to the modulator).

EO amplitude modulator output vs. bias voltage
Click to Enlarge

Figure 3: The output of an EO amplitude modulator as a function of applied voltage when the setup does not include a quarter wave plate, diagrammed in Figure 1. The X marks on the curve correspond to conditions in the table columns.

As discussed in the EO Modulators tab and shown in Figure 3, when a quarter-wave plate is not placed at the input of the EO amplitude modulator (Figure 1), the light input to the modulator is linearly polarized and the applied voltage signal must vary from 0 V to Vπ (or -Vπ to 0 V) to fully modulate the amplitude of input light. The value of Vπ was measured for the EO-AM-NR-C1 and a wavelength of 633 nm using the common method of overmodulating the modulator (apply a peak-to-peak voltage greater than Vπ). Vπ was measured to be 220 V at 633 nm, and Vπ increases linearly with wavelength. As the voltage output of the HVA200 is capped at ±200 V, it cannot supply the voltage range necessary to fully modulate the output signal at this wavelength. If output voltage of the amplifier is saturated in an attempt to drive the modulator, the amplitude of the modulated optical signal will suffer distortion, as shown in Figure 4.

When a quarter-wave plate is placed in front of the modulator, the light entering the EO amplitude modulator is circularly polarized (as shown in Figure 2). The quarter-wave plate essentially adds an optical bias to the light input to the modulator. With this bias, it is not necessary for the voltage signal to vary between 0 and +Vπ or -Vπ in order fully modulate the amplitude of the input light: a drive voltage range of only -1/2 Vπ to 1/2 Vπ is needed to achieve an amplitude maximum and minimum of the optical signal. The table in Figure 5 illustrates the polarization at the output of EO crystal for a range of drive voltages, and the plot shows the amplitude of the light after the polarizer as a function of drive voltage. When a quarter-wave plate is used and the wavelength of the light source is 633 nm, a drive voltage range of ±110 V is required to fully modulate the EO amplitude modulator. This is well within the range of the HVA200, and the fully modulated optical signal produced using this technique is shown in Figure 6.

By including a quarter-wave plate in the optical setup, the available operating range of the amplifier is effectively doubled. With the bias supplied by the quarter-wave plate, the HVA200 is able to drive the EO-AM-NR-C1 across its entire wavelength operating range. This technique also enables the HVA200 to fully modulate the EO-AM-NR-C2 for wavelengths up to 1000 nm. As the price of amplifiers rises dramatically with the maximum voltage output, using this technique can result in significant cost savings. For details on the experimental setup employed and the results obtained, please click here.

EO Modulator Response with Saturated Amplifier
Click to Enlarge

Figure 4: This plot shows the distorted modulation response that results when the amplifier is saturated in an attempt to fully modulate a signal whose Vπ is greater than the maximum driving voltage that can be supplied by the amplifier. The wavelength of this optical signal is 633 nm.
QWP shifts modulator response vs bias voltage
Click to Enlarge

Figure 5: Inserting a quarter-wave plate (QWP) before the EO amplitude modulator, illustrated in Figure 2, shifts the relationship between the output amplitude and the applied voltage. For a bias voltage of 0 V, the output amplitude is halfway between min and max. The X marks on the curve correspond to conditions in the table columns.
Full response of EO modulator when QWP used
Click to Enlarge

Figure 6: This plot shows the undistorted and fully-modulated 633 nm optical signal achieved by inserting a quarter-wave plate into the optical setup as shown in Figure 2, which makes available the full driving voltage range of the amplifier.

HVA200 Connections

Modulation Input Signal

BNC Female

BNC Female

± 10 V, 10 mA

HV Output Monitor

BNC Female

BNC Female

± 10 V, 200 mA, Min Load 50 Ω

HV Output

BNC Female

BNC Female

± 200 V, 100 mA

EO Modulators

RF Modulation Signal - SMA Female

SMA Female

Firmware for the HVA200 Amplifier

The available firmware updates can be downloaded by clicking on the link below.

Software

Firmware Version 3.3 (November 13, 2017)

Firmware files and installer downloads for the HVA200.

Software Download

Posted Comments:
kar-hooi_kuan  (posted 2019-02-20 06:15:13.65)
Hi, I'm interested in Amplitude Modulations EO Modulators. I would like check with you if the optical input can be connectorized with FC/APC connectors? I will need it to be connectorized. If it can be connectorized, could you please quote me together with the EO MOdulator High Voltage driver? By the way, what is the maximum modulation frequency supported by this EO-PM-NR-C3? Thanks a lot.
YLohia  (posted 2019-02-21 08:48:45.0)
Hello, thank you for contacting Thorlabs. Unfortunately, this cannot be connectorized as it requires a collimated free space beam in order to work properly. What wavelength are you hoping to use this for? If it's around the 1550nm range, I would recommend looking into our fiber coupled LN modulators here : https://www.thorlabs.com/newgrouppage9.cfm?objectgroup_id=3918. These can go up to 10 GHz, whereas the model you were interested in is suitable up to only 100 MHz. Another option would be using a FiberBench of at least 70mm length with two Fiberports to make the free space EOMs fiber-compatible. Please see the bottom of this page for more information.
zenin  (posted 2019-02-20 10:42:19.48)
Hi, I am investigating the project of building fast noise eater (faster than 1 MHz) for my free-space lasers by using your EO modulators. I am wondering, can you make EO modulator witohut anti-reflection coating? It is because I have several sources from in VIS and NIR ranges (600-1800 nm). Also I am wondering, can Thorlabs make such noise eater, and if yes, how much will it cost? Looking forward to your reply. Best, Vladimir
YLohia  (posted 2019-02-21 09:02:09.0)
Hello Vladimir, thank you for contacting Thorlabs. Quotes for custom modulators can be requesting by emailing your local Thorlabs Tech Support group (techsupport.se@thorlabs.com in your case). We will reach out to you directly to discuss the possibility of offering uncoated crystals. That being said, please note that the total transmission will suffer greatly when using uncoated crystals. The amplitude modulators consist of two lithium niobate crystals, which means that the reflectivity will be quite high from a total of four surfaces since the optical index is about 2.3. When this happens, you can get multiple reflections within the crystal that see different amounts of modulation and can interfere with each other. The workaround for this would be to tilt the crystal as far as possible and then prevent the reflected beams from getting in the system by clipping them with an aperture or edge of some kind. Unfortunately, we are unable to offer a fully designed 1 MHz noise eater at the moment, though it is something that I will suggest on our internal engineering forum.
vinx-d  (posted 2019-01-17 04:35:15.51)
I am going to use the HVA200 in order to amplify a input voltage. I was wondering if I can amplify the bias without using any input.
YLohia  (posted 2019-04-01 04:43:39.0)
Hello, thank you for contacting Thorlabs. I reached out to you at the time of the original post in order to gather more information about your request. Please send us an email at techsupport@thorlabs.com if you did not receive our email.
kkss0330  (posted 2018-10-11 00:29:20.047)
Hello, I bought EOM that model number of EO-AM-NR-C4, I will operate laser source wavelength 633nm. I know that this supports a wavelength band from 400 to 600nm, can EOM work well from 633nm?
YLohia  (posted 2018-10-11 09:53:27.0)
Hello, thank you for contacting Thorlabs. The -C4 coating typically has a reflectivity of around 0.5-0.7% at 633nm. Since you already have the EOM with you, we recommend that you test it out yourself to see if the change in performance fits your requirements.
baudin  (posted 2018-03-27 16:27:15.35)
Hello, the specs say the load impedance is 14 pF, can you provide the loss angle function of frequency?
YLohia  (posted 2018-04-03 10:26:35.0)
Response from Yashasvi at Thorlabs USA: Hello, thank you for contacting Thorlabs. While we don't have a loss angle as a function of frequency spec at the moment, we do have a spec for the loss tangent @ 400 °C: x-axis: tan(δ) = 0.0006 y-axis: tan(δ) = 0.001 We have seen values around ~0.003 for the loss tangent at 1 GHz. This is a property of the material (lithium niobate) itself.
parksj003  (posted 2018-01-28 22:03:42.99)
I am going to use a HVA200 with EO-AM-NR-C1 for fast light intesnity modulation (on/off). I am wondering the rise/falling time of HVA200 and the time dealy between input and output.
nbayconich  (posted 2018-02-23 10:49:58.0)
Thank you for contacting Thorlabs. The typical rise/fall time of the HVA200 alone is about 350ns at 1Mhz, however the HVA200 is typically limited to the slew rate which is 400V/µs. We have not yet tested time delay when using an intensity EO modulator with the HVA200 at the moment.
tanmaybhwmk3  (posted 2017-11-15 01:51:46.267)
Hi. What is the expected insertion loss of the EO-AM?
tfrisch  (posted 2017-11-20 05:18:05.0)
Hello, thank you for contacting Thorlabs. The loss through the modulator is <1dB, typically about 0.5dB.
fyk15isy  (posted 2017-10-02 15:09:40.037)
Hi! I am looking for an EOM to do an amplitude modulation of 880 nm beam from OPO with an average power of 1 W. (It actually produces 5 ps pulses with 80 MHz repetition rate). I plan to focus the beam into the EOM since my beam diameter is too large for this EOM. Will this EOM be able to withstand this power when using short focal length lenses (50 - 100 mm lenses)?
tfrisch  (posted 2017-11-14 02:48:07.0)
Hello, thank you for contacting Thorlabs. These EOMs are intended to be used with a collimated input. If there is significant convergence or divergence, this would give an angular dependence on the optical path length which would affect the retardance and therefore amplitude modulation. I will reach out to you directly about damage and other methods of limiting the beam diameter.
user  (posted 2017-05-02 11:05:15.013)
What's the LiNbO3 crystal length of EO-AM-NR-C1? 20 mm?
nbayconich  (posted 2017-05-03 10:04:19.0)
Thank you for contacting Thorlabs. The crystal length of our free space Amplitude modulators is 20mm. The LiNbO3 crystals in our free space phase modulators are 40mm in length. A tech support representative will contact you directly.
melanie.lebental  (posted 2017-02-06 09:19:47.293)
Hello, Please, what is the maximal speed of modulation from 0 to Vpi for the wavelength 532 nm ? 100 kHz ? 1 MHz ? Best regards,
tfrisch  (posted 2017-02-14 02:10:19.0)
Hello, thank you for contacting Thorlabs. The maximum frequency will depend on the max current that can be supplied by the voltage driver, and the function of that signal. In the case of a sine wave, the maximum frequency is Imax/(pi*Vpp*C) where Imax is the max current of the driver, Vpp is the peak to peak voltage of the signal, and C is the capacitance of a non-resonant modulator (14pF for our units). I have contacted you with information on this derivation.
parksj003  (posted 2016-12-01 16:27:36.453)
Hello, I am looking for fast polarization modulator. The sorce we are using is femto-seond laser (wavelength ranging from 700-1000 nm, Power ~3W, beam diameter ~1.5mm). I think EO-AM-NR-C1 might be fine, as it can fastly alternate the laser beam polarization (but I am not sure yet). We need to alternate the beam polarization either vertically or horizontally (with a speed of at least 5 kHz). Would you let me know if there is proper solution for us? Best, Seongjun
tfrisch  (posted 2016-12-01 08:41:41.0)
Hello, thank you for contacting Thorlabs. I'd like to ask a few questions about your laser, so I will contact you directly about that. As for changing the polarization state, in general, that is how these freespace amplitude modulators work, you would just not use an output polarizer to drop the intensity for the state crossed to the input state. If your input is vertical, then a voltage of Vpi would give horizonatally polarized light. The fast axis of the crystal is at 45 degrees with respect to the housing, so you may use horizontal or vertical input.
gksthf666  (posted 2016-11-22 05:18:04.04)
To whom it may concern, Hi, I'm Hansol Jang and I need some resonant type amplitude modulator with following properties. 1. Resonant frequency : 80 MHz 2. AR coating : 600 - 900 nm (actually, I need 750 to 1000 nm range) 3. Polarization : Schematic diagrams shown in website are pretty confused.. Which one is correct? (single crystal with linear polarizer or dual crystals) It is suitable for my system that input and output polarization is vertically or horizontally changed with respect to base (bottom) of EOM module. Best, Hansol Jang
tfrisch  (posted 2016-11-22 07:32:36.0)
Hello, thank you for contacting Thorlabs. For your first two notes, we can provide a quote for you. As for the polarization, the free space amplitude modulators use two LiNbO3 crystals which have their fast axes offset to mitigate changes in birefringence due to thermal effects. These are mounted at +45 degrees and -45 degrees with respect to the housing, so for the best extinction, the input polarization state should be vertical or horizontal. The EOM introduces an ellipticity to the polarization state, so an output polarizer will cause the change of amplitude. This output polarizer can be either parallel to or crossed to the input polarization (horizontal or vertical).
jchg2758  (posted 2016-08-29 12:33:53.187)
Hello, Recently I used the eo phase modulator for generating 2 MHz sidebands on 80 MHz rep. rate frequency comb. A RF signal generator makes 20 dBm 2 MHz signal and your company's 200 V amplifier makes additional bias and amplification. However there is only -70~-80 dBm sidebands and it hard to find the decreasing of fundamental. I set the vertical pol. input and enough optical power. Is there any mistake about choosing product? align miss? lack of amplification? I'm look forward to your answer. Thanks.
tfrisch  (posted 2016-09-01 11:47:51.0)
Hello, thank you for contacting Thorlabs. The relative intensity of sidebands will be dependent on the modulation depth of the phase. The relation between voltage depth and phase modulation depth is wavelength dependent. I will contact you directly about your application.
killian  (posted 2016-08-03 11:14:04.56)
Hello, I am looking for an EOM to use as a phase modulator for both 532 nm and 1064 nm light. The beams are CW, co-propagating. I would need an AR coating that covers both wavelengths because I don't want much loss passing through the EOM. Can you provide a specialty coating? The biggest requirement though is the variation in the half-wave voltage with wavelength. I need a controllable, differential phase shift of the 532 and 1064 nm light. In other words, I need a material for which the half-wave voltage deviates as much as possible from being linear with wavelength. I want to be able apply a voltage and shift the 1064 one wavelength while shifting the 532, for example, 2.5 wavelengths instead of two. It doesn't have to be exactly that, but I need the differential control of the relative phases. The provided curves for Lithium Niobate look promising. If I can apply up to about 1000V, I can shift the 1064 phase 2 wavelengths, while shifting the 532 4.5 wavelengths, which would be just enough for my application. What is the peak DC voltage that can be applied to your phase modulators? Thanks, Tom
gkatsop  (posted 2016-02-05 18:27:12.06)
Hi. We are interested in modulating the polarization of a 1315nm laser (from right-circular to left-circular polarization and back) at a frequency of a few kHz, using your EO-AM-NR-C3. However we notice that your HVA200 amplifier provides a +/-200V output, whereas the half-wave voltage at 1315nm is around 450V. Supposedly then, the HVA200 is of no use for us and we would have to search for another amplifier, correct? Is there something you could propose in this direction? Is this EOM otherwise ok with our application? Kind regards, George.
besembeson  (posted 2016-02-10 12:47:22.0)
Response from Bweh at Thorlabs USA: With a suitable driver and a quarter waveplate in a rotation mount at the input, and a linear polarizer and quarter waveplate at the output, you should be able to achieve this. We will contact you with suggestions for high voltage amplifiers.
peh  (posted 2015-10-22 17:53:25.073)
Is it possible to use a modulation signal with the following properties together with the HVA200 and E=-AM-NR-C4? repetition period 100 µs High signal time 1 µs
besembeson  (posted 2015-10-28 11:16:54.0)
Response from Bweh at Thorlabs USA: The slew rate for the HVA200 is 400V/us. If you require up to V_pi, for the EO-AM-NR-C4, you will need about 200V maximum (at 600nm for example), which will take about 0.5us at best from the HVA200 so you will end up with an almost triangular waveform, instead of a 1us/100us square wave. The shape of the waveform will vary depending on your wavelength and voltage requirement. If the 1us (High signal) excludes the voltage ramp up time, then this could be suitable.
cweidner0  (posted 2015-02-10 11:35:56.063)
Is this EOM suitable for use in interferometric applications? Is there significant wavefront distortion as the laser passes through the crystal? Has this distortion been quantified in any way?
besembeson  (posted 2015-02-12 12:05:11.0)
Response from Bweh at Thorlabs USA: We don't have data yet quantifying the transmitted wavefront error for these devices. I will followup by email to discuss your application further.
user  (posted 2014-10-29 12:56:55.817)
Wondered if HVA200 includes a BNC cable? It would be better for us to know on a webpage if there is chart telling us what are included.
jlow  (posted 2014-10-30 01:46:14.0)
Response from Jeremy at Thorlabs: Thank you very much for your feedback. The HVA200 includes a BNC to SMA cable. We will look into adding this on the website.
aklossek  (posted 2014-10-22 14:09:33.31)
Dear ladies and gentlemen, please tell me the total geometrical length of the lithiumniobat crystals within the EO-AM-R-20. I need this to compensate the delay caused by this optic. Best regards André Klossek
jlow  (posted 2014-10-22 01:53:19.0)
Response from Jeremy at Thorlabs: The amplitude modulator has two crystals and each one is 20mm long.
aklossek  (posted 2014-10-16 10:16:47.867)
Dear ladies and gentlemen, I am interested in your EO-AM-R-20-C1. My question is about the temperature stability. Does the EOM need some specified, stable climate conditions (temperature)? Best regards André Klossek
jlow  (posted 2014-10-22 03:57:46.0)
Response from Jeremy at Thorlabs: The amplitude modulators are made with 2 crystals oriented 90° from each other. This configuration greatly reduces the temperature sensitivity so you can use this in a regular lab environment. I will contact you directly to discuss about this further.
h.schultheiss  (posted 2013-10-17 16:12:25.66)
Hello, I plan on using one of your modulators for the generation of sidebands with a frequency separation from 1 GHz to 20 GHz. I used already your phase modulator for this purposes and it works for a couple of frequencies, but now want to build a new setup and I was wondering, if I could use the amplitude modulator as well. What is actually the difference between the amplitude and the phase modulator, the price is the same. Best wishes, Helmut Schultheiß
jlow  (posted 2013-10-17 16:29:00.0)
Response from Jeremy at Thorlabs: The phase modulator is made with one long crystal whereas the amplitude modulator is made with two crystals, oriented at 90° to each other, and oriented 45° relative to the horizontal (see the picture on the amplitude modulator subgroup). With a horizontally or vertically polarized beam, the amplitude modulator is actually acting more as a variable wave plate and it requires a linear polarizer on the output to make it an actual amplitude modulator. In theory you could use the amplitude modulator to generate sidebands but this can be done much better with the phase modulator. We will contact you directly to discuss about this further.
ahmmadvand  (posted 2013-08-09 14:14:19.96)
Is it possible to produce circular polarization by using an electro optic modulator? What are the advantages/disadvantages in comparison to photo-elastic modulator (PEM). I would like to know the best way for producing circular polarization by using thorlabs products.
cdaly  (posted 2013-08-15 16:16:00.0)
Response from Chris at Thorlabs: Thank you for using our feedback tool. Using a phase modulator is going to involve a relatively complex setup to create polarization. If you are looking to create a circularly polarized free space beam, I would recommend using a 1/4 wave plate for a linearly polarized source. If your source is randomly polarized, I would say t just pass it through a polarizer initially, then through the quarter waveplate.
jpott  (posted 2013-05-17 08:56:50.653)
I have a questin to your broad-band phase modulators: what is the broadband phase behaviour: will a given voltage result in the SAME phase over all frequencies within the passband, or does the phase-modulator introduce voltage-dependent dispersion? thanks - j-uwe pott
tcohen  (posted 2013-05-23 13:39:00.0)
Response from Tim at Thorlabs: The voltage to get a given phase is a function of wavelength. You can see the half-wave voltage vs. wavelength in the manual on page 4. I will contact you to discuss this further.
proto.vladimir  (posted 2013-05-02 18:35:23.707)
1). AOM: in the figure with two crystals in series: is it true that the voltages are applied in the same polarity with respect to optical axis direction? 2). POM: what is the phase change at half-wave voltage Ul/2? 3). POM-AOM: why Ul/2 is 2 times bigger for AOM relative to POM?
cdaly  (posted 2013-06-12 16:03:00.0)
Response from Chris at Thorlabs: Thank you for using our feedback tool. The image on the web indicating the orientation for the crystal axis and voltages as of 6/12/13 is incorrect in this regard and we will have this updated just as quickly as possible. Thank you for pointing it out. The nominal Vpi of PM is 2/3 of the Vpi of AM as the curve shows is due to the polarization direction of the light relative to the crystal axis. For AM modulations, the light is polarized 45 degree to the axis, and both crystal pieces contribute to phase shift equally. The phase shift in this case is mainly decided by the difference of the EO coefficients (r33-r11). For PM modulation, the light is supposed to be polarized along the Z axis to maximize the EO effect, therefore its phase shift is decided by r33 only.
sharrell  (posted 2013-06-14 15:02:00.0)
Additional Response from Sean at Thorlabs: The image of the crystal axes, voltages, and polarization has been updated today (6/14/2013). Thanks again for bringing it to our attention.
bdada  (posted 2011-11-04 11:37:00.0)
Response from Buki at Thorlabs: Thank you for your inquiry. For 925nm I would recommend the –C2 units which have the AR coating for 900-1250nm. We have sent you additional information on the reflection from each surface - it is much less than 0.5% over the 900-1250nm range. Please coontact TechSupport@thorlabs.com if you have further questions.
yuilon  (posted 2011-11-02 09:30:26.0)
I concern the product EO-PM-NR-C2, how much power lost inside EOM assuming in coming laser is CW 925 nm with power 1 W/mm2?
bdada  (posted 2011-09-15 14:55:00.0)
Response from Buki at Thorlabs: Yes, the EO-AM-NR-Cx modulators will work for a pulsed laser. The primary concern, however, is the optical power level that causes photorefractive damage to the Lithium Niobate (LN) crystal. The LN crystals used in the Thorlabs EO modulators are MgO doped which increases the photorefractive damage level to 2W/mm2 @ 532 nm and 4W/mm2 @ 1064 nm. The photorefractive damage level is highly dependent on wavelength, decreasing rapidly at wavelengths below 532 nm. For the C1 wavelength range (600-900 nm) it would be conservative to use the 2W/mm2 damage threshold level. For the C2 wavelength range (900-1250 nm), use the 4W/mm2 damage threshold level. These damage power levels are for CW power. The question is how does this scale to peak power levels for pulsed operation. It is very difficult to answer this question, there is no simple answer because in the end it will depend upon pulse width, duty cycle, peak power and wavelength. Based upon some measurements that we have been making recently to address this issue, it appears that for short pulses (< 1 ns) and low duty cycle (< 0.2%) pulsed lasers, the damage level for the average power is approximately 50% of the CW damage level. So, for example, the damage threshold for a short pulse, low duty cycle laser in the 600-900 nm range is an average power of approximately 1W/mm^2. Please contact TechSupport@thorlabs.oom if you have further questions.
cyjiang  (posted 2011-09-13 09:19:48.0)
I want to know whether the EO-AMNR-C1 and C2 could work properly for pulsed laser. The pulse width is 2 ps and the average power of the pulse is 1 mW. Thank you very much.
bdada  (posted 2011-08-22 16:48:00.0)
Response from Buki at Thorlabs: Thank you for your feedback. We have contacted you to verify the details of your set up.
eexjw1  (posted 2011-08-22 11:25:05.0)
I tested the stability of EO-PM-NR-C1 before it is installed into the system. The modulation frequency from HV amplifier is 1kHz at 120V, laser power is 15 mW, with a diameter of 1mm, which are all within the range for EOM use. The problem is that the signal has a sinusoidal drift with a period of 15 ~ 20 min, and the signal goes to absolutely zero during the drifting. What may be the reason for this? Has this ever happened before?
jjurado  (posted 2011-08-12 13:35:00.0)
Response from Javier at Thorlabs ti cev136: I will contact you directly to assist you with your application.
cev136  (posted 2011-08-12 09:52:41.0)
Does not work at DC for 400nm light.
jjurado  (posted 2011-08-02 15:08:00.0)
Response from Javier at Thorlabs to cyjiang: At a power output on 1 W and 1 mm diameter, the power density is then 1 W/[pi x (0.5mm)^2] = 1.3 W/mm^2, which is below the maximum recommend input of 4W/mm^2 at 1064 nm. The EO modulator should work well under this condition.
cyjiang  (posted 2011-08-02 13:48:42.0)
In the manual it is said that the Maximum Optical Power Density of EO-AM-NR-Cx is 2W/mm2 at 532nm and 4W/mm2 at 1064 nm. We have a 1064 nm laser beam with a power of 1 Watt and a diameter of 1 mm. Would it work properly at such condition? Or will there be any problem for handling such laser beam by using these modulators?
jjurado  (posted 2011-06-23 20:02:00.0)
Response from Javier at Thorlabs to cumn333: Thank you very much for contacting us. We currently do not have data regarding the performance of our EO modulators when subjected to femtosecond laser pulses. Nonlinear effects such as self-focusing and self phase modulation might take place when using a femtosecond source, but we unfortunately do not have a quantitative analysis for these effects and how they affect the LN crystals. However, the main concern is the potential photorefractive damage that will most likely occur at the 900 nm wavelength and 2 W power range. Based on the damage threshold guidelines for these modulators (4W/mm^2 at 1064 nm), these modulators will most likely not work for your application. I will contact you directly for further assistance.
cumn333  (posted 2011-06-21 14:35:31.0)
I wonder if your EO phase modulator can work with femtosecond pulses from Ti:sapphire lasers. For example, power=2Watt, Wavelength=900nm, Reprate=80MHz, pulse duration = 150 fs. I am worried about that the light intensity is strong enough to cause nonlinear interaction with the crystal. Customer Email: cumn333@yahoo.com This customer would like to be contacted.
jjurado  (posted 2011-05-06 16:47:00.0)
Response from Javier at Thorlabs to bradoptics: Thank you very much for contacting us with your request. The term "broadband" is used to describe the operating wavelength range, which, for the EO-AM-NR-C4, is 400-600 nm. Regarding the bandwidth, the broadband modulators can operate from DC to 100 MHz. I will contact you directly for further support.
bradoptics  (posted 2011-05-06 14:52:55.0)
I had a question about the bandwidth of the E0-AM-NR-C4. Its listed as "broadband" on the spec sheet. Could I use it from DC to 1MHz?
jjurado  (posted 2011-03-30 10:23:00.0)
Response from Javier at Thorlabs to carlos.camargo: Thank you very much for contacting us. The EO-AM and EO-PM electro-optic modulators are designed for freespace input (and output). They have an input clear aperture of 2 mm. I will contact you directly for further assistance. You can also check the manual for more information: http://www.thorlabs.com/Thorcat/15900/15956-D02.pdf
carlos.camargo  (posted 2011-03-30 09:20:14.0)
A dummy question: How does the light enter in the EOM? By fiber or directly the light beam? How does it out?
Thorlabs  (posted 2010-07-12 15:05:53.0)
Response from Javier at Thorlabs to martensites: thank you for your feedback. We have not tested the maximum peak-to-peak voltage that the EO modulators can withstand. However, we do know that the crystal should perfom well and without any risk of damage at an input of +/- 240 V.
martensites  (posted 2010-07-12 01:57:57.0)
Please let me know the range of operating voltage of the EOM. Is it possible working on +- 240 V? (+-half wave voltage)
jjurado  (posted 2010-06-01 21:26:42.0)
Response from Javier at Thorlabs to andriyc: the common term used in amplitude/phase modulators is contrast ratio, which depends on factors such as input beam diameter, alignment through the crystal, extinction ratio of polarizers, and linewidth of laser source. The key parameter will be beam diameter; at ~1mm, contrast ratios on the order of 20:1 are typical. As the beam diameter decreases to around .5mm, typical values are on the order of 50:1. Also, focusing the beam can lead to higher contrast ratios, however you must be careful not to damage the crystal by incurring high power densities. You can also use pinholes to increase the contrast ratio well above 100:1. The C4 in the EO-AM-NR-C4 defines the anti-reflective coating, which covers 400-600nm, with a reflectivity < 0.5%. Though the reflectivity will not be as low, this modulator can still be used at 650nm with low reflectivity, in the order of <2%.
andriyc  (posted 2010-05-31 09:42:45.0)
What is the extinction ratio (of polarizations) for EO Amplitude Modulators (for ex. EO-AM-NR-C4). Also, could EO-AM-NR-C4 be used for modulating wavelengths up to 650 nm? The division into versions Cx comes only from anti-reflection coating?
Adam  (posted 2010-05-26 17:09:56.0)
A response from Adam at Thorlabs to andriyc: The amplitude modulators can be used to modulate the polarization of the light as long as the incoming light is polarized.
andriyc  (posted 2010-05-26 14:03:03.0)
Is it possible to use Thorlabs EOM for modulation of the polarization?
Adam  (posted 2010-04-21 08:54:43.0)
A response from Adam at Thorlabs to pmd: At this time, there are no plans to add BBO or KDP crystals in our modulator line. However, I like the idea of offering modulators that work in the UV range and will mention your idea to our engineers as a customer inspired new product idea.
pmd  (posted 2010-04-21 00:52:49.0)
When will you add other crystals, like BBO and KDP to have modulators that are good in the UV? Thanks, Pedro.
Greg  (posted 2010-04-13 17:16:01.0)
A response from Greg at Thorlabs: We have added specifications to the Specs tab regarding the High Q Resonant option modulators. More information will be added on these modulators shortly.
user  (posted 2010-01-16 13:18:45.0)
The presentation mentions but then doesnt provide any details on the: High Q Resonant Option. Are there specifics that could be added to help the reader understand what Thorlabs has to offer.
apalmentieri  (posted 2009-12-15 13:05:20.0)
A response from Adam at Thorlabs: At this time we do not offer high voltage amplifiers that will operate with bandwidths greater than 1MHz. If your modulation frequency is fixed, you may be able to use a resonant modulator. This will make your Q factor ~10 so your halfwave voltage will be ~20V @633nm. This will be much more manageable in terms of finding the appropriate driver electronics. I will email you with more information about pricing and lead time for these custom products. Please note that if you need to modulate from 20Mhz -50MHz a broadband modulator may be necessary and it becomes more difficult to find the appropriate driver electronics. I will email you with some suggestions for these as well.
stephanos  (posted 2009-12-14 14:22:12.0)
I noticed that although your modulators have a bandwidth of up to 100Mhz, the voltager amplifier you provide only has a bandwidth of 1MHz. I am interested in a broadband Amplitude modulator that uses EO Modulators in the visible wavelength (400nm-670nm) that I can pulse modulate (digital input signals) and the resultant optical output can be pulse widths ~ 2nsec at rep rates of 10MHz-50MHz, with good extinction ratio (better than 200:1). Does Thorlabs have such a solution for me? Feel free to contact me directly on my cell (408) 849-6619 or via e-mail: Stephanos@Oramic.com
Laurie  (posted 2008-12-09 10:27:02.0)
Response from Laurie at Thorlabs to lsandstrom: Thank you for your feedback. The units are radians.
lsandstrom  (posted 2008-12-09 10:15:55.0)
What is the units on the axis in Fig. 1 in the graph tab?

EO Amplitude Modulators

Amplitude Modulator Crystal Orientation
Click to Enlarge

Amplitude Modulator Crystal Orientation

The electro-optic amplitude modulator (EO-AM) is a Pockels cell type modulator consisting of two matched lithium niobate crystals (see the diagram to the right) packaged in a compact housing with an RF input connector. Applying an electric field to the crystal induces a change in the indices of refraction (both ordinary and extraordinary) giving rise to an electric field dependent birefringence which leads to a change in the polarization state of the optical beam. The EO crystal acts as a variable waveplate with retardance linearly dependent on the applied electric field. By placing a linear polarizer at the exit, the beam intensity through the polarizer varies sinusoidally with linear change in applied voltage.

Please note that AM modulators operating in the -C4 band (400 - 600 nm) should only be used for AC modulation above a few Hz. MgO-doped lithium niobate can be sensitive to light in this wavelength range, displaying a slow negation to an applied DC field. The more intense the light, the faster the DC field is cancelled. Hence, in practice, a DC voltage cannot be used to bias the modulator at the desired operating point. Instead, an adjustable wave plate can be employed to optically bias the modulator to the desired operating point (please see the Lab Facts tab for more information on proper modulator biasing).

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EO-AM-NR-C4 Support Documentation
EO-AM-NR-C4EO Amplitude Modulator, Wavelength: 400 - 600 nm
$2,600.24
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EO-AM-NR-C1 Support Documentation
EO-AM-NR-C1EO Amplitude Modulator, Wavelength: 600 - 900 nm
$2,600.24
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EO-AM-NR-C2 Support Documentation
EO-AM-NR-C2EO Amplitude Modulator, Wavelength: 900 - 1250 nm
$2,600.24
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EO-AM-NR-C3 Support Documentation
EO-AM-NR-C3EO Amplitude Modulator, Wavelength: 1250 - 1650 nm
$2,600.24
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EO Phase Modulators

Our EO phase modulators provide a variable phase shift on a linearly polarized input beam. The input beam is linearly polarized along the vertical direction which is the Z-axis of the crystal. A voltage at the RF input is applied across the Z-axis electrodes inducing a change in the crystal's extraordinary index of refraction thereby causing a phase shift in the optical signal.

The control signal may be a DC or a time varying RF signal. When the control voltage is a time varying signal, the optical beam undergoes frequency modulation whereby some of the energy at the fundamental frequency is converted into sidebands separated from the fundamental frequency by the integer multiples of the modulating frequency. The amount of energy converted into sidebands is determined by the depth of modulation. The graph to the right shows a plot of relative sideband strength as a function of depth of modulation.

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EO-PM-NR-C4 Support Documentation
EO-PM-NR-C4EO Phase Modulator, Wavelength: 400 - 600 nm
$2,600.24
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EO-PM-NR-C1 Support Documentation
EO-PM-NR-C1EO Phase Modulator, Wavelength: 600 - 900 nm
$2,600.24
5-8 Days
EO-PM-NR-C2 Support Documentation
EO-PM-NR-C2EO Phase Modulator, Wavelength: 900 - 1250 nm
$2,600.24
5-8 Days
EO-PM-NR-C3 Support Documentation
EO-PM-NR-C3EO Phase Modulator, Wavelength: 1250 - 1650 nm
$2,600.24
Lead Time

Resonant EO Modulators

Our resonant EO phase modulators feature a high Q, and can be driven by a standard laboratory function generator. The high Q resonant tank circuit located inside the modulator boosts the low level RF input voltage from a standard function generator to the high voltage needed to achieve full depth of modulation. This results in a Half-Wave Drive Voltage of only 15 V at 633 nm.

Resonant modulators are offered in both Phase- and Amplitude-modulating versions, operating at 20 MHz with a 1 MHz bandwidth. They feature a C1 coating for use from 600 to 900 nm. Custom versions are also available, with user-specified resonant frequencies from 0.1 to 100 MHz and a variety of AR coatings.

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EO-PM-R-20-C1 Support Documentation
EO-PM-R-20-C1Electro-Optic Resonant Phase Modulator, 20 MHz, 600-900 nm
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EO-AM-R-20-C1 Support Documentation
EO-AM-R-20-C1Electro-Optic Resonant Amplitude Modulator, 20 MHz, 600-900 nm
$3,212.73
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High Voltage Amplifier for EO Modulators and Shear Piezo Actuators

  • ±200 V Bipolar Output
  • 100 mA Pulsed Output Current (100 mA Continuous)
  • 1 MHz Bandwidth
  • Low Noise
  • -20X Voltage Gain
  • CE Compliant

The Thorlabs HVA200 High Voltage Amplifier is a preferred driver for our Electro-Optic (EO) Modulators, as well as our Shear Piezo Chips. With a voltage gain of -20, the amplifier produces a maximum output voltage of ±200 V, a continuous current output of 100 mA, a 1 MHz bandwidth, and low noise. An adjustable bias allows for precise DC offset control. For our EO modulators, this amplifier produces a maximum 200 V half-wave voltage. This is ideal for driving our non-resonant EO phase modulators to fully modulate optical signals with wavelengths up to approximately 900 nm. When the HVA200 is used to drive our EO amplitude modulators, the effective voltage range of the amplifier can be extended using the technique described in the Lab Facts tab. Using that approach, the HVA200 can drive the EO-AM-C1 to fully modulate all optical signals within its wavelength range and the EO-AM-C2 to fully modulate optical signals with wavelengths up to 1000 nm. When the technique is not used, the HVA200 can drive the EO amplitude modulators to fully modulate optical signals with wavelengths up to approximately 620 nm.

The HVA200 uses a high voltage, wideband, high slew rate output amplifier to achieve the desired output. The input amplifier includes a summing junction, which allows an adjustable DC bias to be added to the input modulation. This composite signal is then boosted by a fixed voltage gain of 20 by the output amplifier up to a maxiumum output of ±200 V. For example, if the HVA200 is sweeping from -200 to 200 V and a 10 V DC Bias is applied, the output of the HVA200 will be from -190 to 200 V (i.e., the sweep is clipped because the maximum voltage output was reached). If, however, the HVA is swept from -100 to 100 V and the same 10 V DC Bias is applied, the output will sweep from -90 to 110 V.

For added safety, a front panel HV Enable button must be pressed to connect the HV output to the output BNC. The DC Bias control consists of a rotary encoder, which allows precise control and repeatability. The bias adjustment is typically used to shift the DC level of the output as needed by the application. A voltage monitor output is provided to allow real-time monitoring of the high voltage output. The monitor has a scaling of 20:1 (when used with high impedance detectors) so that an output of 200 V results in a 10 V monitor voltage.

The HVA200 includes an SMA-to-BNC cable for connection to our free-space electro-optic modulators, a USB 2.0 Type A to B cable for remote operation, and a power cord. Custom cables will need to be used to connect the HVA200 to one of our shear piezos.

HVA200 Pin Diagrams

Modulation Input Signal
BNC Female
HV Output Monitor
BNC Female
HV Output
BNC Female
EO Modulators
RF Modulation Signal - SMA Female
BNC Female BNC Female BNC Female SMA Female
± 10 V, 10 mA ± 10 V, 200 mA, Min Load 50 Ω ± 200 V, 100 mA
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HVA200 Support Documentation
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Electro-Optic Modulator Glan Thompson Polarizer Mounting Adapter

EO-PMT Polarizer Mounting Adapter
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EO-PMT Polarizer Mounting Adapter
  • GTH5M Mounting Adapter for Our Electro-Optic Modulators
  • Easily Rotates Into and Out of Beam Path
  • Ø13 mm Aperture for Use with GTH5M
  • 2-56 Mounting Screw and Washer Included

The EO-PMT allows for easy interfacing of a Glan Thompson polarizer (GTH5M) to our Electro-Optic Modulators. The single mounting point allows the mount to swivel the polarizer into and out of the light path; a useful feature that allows for alignment and adjustment of the electro-optic modulators. The EO-GTH5M packages the Glan Thompson polarizer (GTH5M) with the mounting adapter.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Universal Price Available
EO-PMT Support Documentation
EO-PMTGlan Thompson Polarizer Mounting Adapter
$28.37
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EO-GTH5M Support Documentation
EO-GTH5MGlan Thompson Polarizer Mounting Adapter with GTH5M
$474.87
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EO Modulator Mounting Accessories

Our EO Modulators Can Be Mounted Using the PY005 5-Axis Stage, FT-EOMA Bracket and PY005A1 Base (Left) for a 2" (50.8 mm) Beam Height or Directly to the PY005 Stage (Right)

FT-EOMA EO Modulator Application Shot
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EO Modulator Mounted in a FiberBench Using the FT-EOMA Adapter
  • Compact Platform with Five Axes of Adjustment
  • Adapter Bracket Mounts Modulator to the Platform or any FiberBench Over 70 mm Long
  • PY005A1 Mounting Base Mounts EO Modulators with a 2" (50.8 mm) Nominal Beam Height when used Together with the PY005 and and FT-EOMA
  • Mounting Screws Included with All Mounting Adapters

The PY005 is a compact stage with five degrees of freedom. Two actuators adjust the yaw and Y axes, two actuators adjust the pitch and Z axes, and a single actuator adjusts the X axis. Click here for full information about the PY005 stage.

An EO modulator can be mounted directly to the PY005 using the #8 counterbore accessible from the bottom of the stage (shown to the far right). This counterbore is accessible even when the PY005A1 base is attached to the stage. Additionally, the EO modulator can be mounted to the stage using the FT-EOMA adapter bracket (shown to the immediate right). When the FT-EOMA is used to mount the modulator and the PY005A1 mounting base is attached to the bottom of the stage, the optical axis of the EO modulator is positioned at a nominal height of 2" (50.8 mm) from the optical table.

The FT-EOMA adapter bracket can also be used to mount a Modulator onto a FiberBench. The length of the bench needs to be at least 70 mm to mount the modulator. Incorporation of the optional EO Modulator optic mount and polarizer (EO-GTH5M) will require a longer FiberBench. The Linear Polarizer modules are well suited for use with an EO Modulator in a FiberBench System. The application picture to the right shows an EO Modulator with an FT-38X100 Multi-Axis FiberBench, one Linear Polarizer, and two FiberPorts.

Based on your currency / country selection, your order will ship from Newton, New Jersey  
+1 Qty Docs Part Number - Imperial Price Available
PY005 Support Documentation
PY005Compact Five-Axis Stage, 27.4 mm (1.08") Deck Height
$409.94
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PY005A1 Support Documentation
PY005A1Slotted Mounting Base for PY005 5-Axis Stage, 1.44" Deck Height
$27.06
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+1 Qty Docs Part Number - Universal Price Available
FT-EOMA Support Documentation
FT-EOMAAdapter Bracket for EO Modulators and FiberBenches or PY005(/M) Stage
$50.70
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+1 Qty Docs Part Number - Metric Price Available
PY005/M Support Documentation
PY005/MCompact Five-Axis Stage, 27.4 mm (1.08") Deck Height, Metric
$409.94
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PY005A1/M Support Documentation
PY005A1/MSlotted Mounting Base for PY005/M 5-Axis Stage, 36.6 mm Deck Height, Metric
$27.06
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