The IPM5300 is a fiber optic polarimeter that enables high speed measurements of the State of Polarization (SOP). The in-line fiber design provides an insertion loss of less than 1.1 dB, a dynamic range of 45 dB, and an accuracy of ±0.25° on the Poincaré Sphere with a sampling rate of 1million complete SOP measurements per second. The all fiber polarimeter is based on patented Fiber Bragg Grating (FBG) Technology. Its novel combination of in-line polarimetric measurement, low insertion loss, high speed, and accuracy enables unprecedented measurement of the state of polarization in fiber optical applications. For more information, please see the Operation tab.
All four Stokes values, which fully characterize a SOP, are provided either as analog output voltages or as digital values to the PC. The SOP measurement can be controlled via an external trigger function allowing the synchronization of the IPM5300 with other devices. The update rate of 1 MHz applies to the fully characterized SOP measurement.
The IPM5300 is based on the Thorlabs TXP5000 Modular Test & Measurement System and is controlled by a PC via easy to use graphical user interfaces (see User Interface tab). It offers additional features like USB/Ethernet ports, plug and play combination with other modules, and flexible configuration via LabVIEW™, LabWindows/ CVI™, MSVC and Borland C drivers.
|Wavelength Range||1510 - 1640 nm|
|Insertion Loss (w/ Connectors)||< 1.2 dB|
|Dynamic Range||45 dB|
|Sampling Rate||3 S/s - 1 MS/s (Selectable)|
|Max Input Power||+15 dBm|
|Measurable SOP States||Full Poincaré Sphere|
|Averaging Time Continuous Mode||10 µs - 300 ms|
|Averaging Time Buffered Mode||1 µs - 300 ms|
|SOP Accuracy||±0.25 ° on Poincaré Sphere*,**|
|DOP Accuracy||±0.25 %*|
|Relative Power Measurement Accuracy||±0.01 dB*|
|Absolute Power Measurement Accuracy|
(Pinput > -20 dBm)
|Operating Input Power Range||45 dB, -30 to 15 dBm|
|DOP measurement Resolution||0.01%|
|SOP Measurement Resolution||0.01°|
|s1, s2, s3 Measurement Resolution||0.0001|
|Analog Monitor Output||-2.5 to 2.5 V|
|General Technical Data|
|Operating Temperature||5 to 40 °C|
|Storage Temperature||-40 to 70 °C|
|Optical Input/Output Connector||FC/APC|
|Optical Fiber||Standard Single Mode Fiber for 1550 nm|
|Optical Fiber Numerical Aperture||0.11|
|Warm-up Time for rated Accuracy||10 min|
|Mechanical Width||2 Slots in TXP Chassis|
The IPM5300 polarimeter is an in-line polarimeter that utilizes custom Fiber Bragg Gratings (FBGs). See Figure 1 for a diagram of the optical schematic of the polarimeter module. The device uses two pairs of FBGs whose reflectivity is polarization dependent, to direct very small percentages of the transmitted optical power to four detectors. A λ/4 fiber waveplate is positioned between the two pairs of FBG's to produce the two additional elliptical states of polarization.They are required for a full analysis of an arbitrary state of polarization. TheIPM5300 overcomes the limitations of other fiber based in-line polarimeter designs by eliminating the need to use tap couplers which show significant temperature and wavelength sensitivity. The FBG approach offers superior performance; it provides an extremely broad wavelength range (1200nm-1700nm) as well as highly accurate SOP and DOP measurements.
Thorlabs IPM5300 in-line polarimeter measures the four stokes parameters of the signal to determine the State of Polarization (SOP). The resulting SOP can then be presented either on the Poincaré Sphere, the Polarization Ellipse or in time domain (See User Interface tab). The IPM5300 can be activated in two modes: single mode or array mode.
In this mode the polarimeter measures one state of polarization after another. There is no defined time scale. If one measurement has finished and the data is transferred to the PC, the next measurement starts. The results can be taken from the analog output or can be displayed through the GUI.
This mode should be used when there is no fast polarization change that can be observed by the user.
In this mode sample rate and the number of measurement points (max. 1024) are predetermined. The complete measurement results are transferred to the PC after all n points are measured. This allows having a defined time scale for the measurement as well as a hardware trigger and the registration of pre-trigger samples. The data can then be displayed graphically or numerically on the GUI. This mode is ideal when fast SOP changes occur (see Application tab for a specific example). The measurement results can be saved in an ASCII file.
The standard fiber connection for input and output is FC/APC, however, other connections are available upon request. The SOP at the output is different from the measured SOP since there is a single mode fiber between the actual in-line polarimeter and the output port. This fiber will transform the polarization.
The in-line polarimeter IPM5300 measures the State of Polarization (SOP), the Degree of Polarization (DOP) as well as the signal's power. The graphical user interface can present the data in one of the following graphical interfaces: a Poincaré Sphere, a Polarization Ellipse or on a time domain chart. Additionally, the data can also be displayed numerically.
The Poincaré Sphere window shows you the actual status of the output polarization on the transparent sphere and also shows numerically the three stokes parameters s1, s2 and s3. To distinguish between two opposite modes the Polarization states on the front side of the transparent sphere are shown in red, on the rear side in blue. The user interface allows rotating and zooming into the Poincaré sphere.
Another representation of the polarization status is shown as polarization ellipse, with numerical values for the Ellipticity and Azimuth angle. 'R' or 'L' are shown on the display for right- and left-handed polarization.
In the Chart mode the user can view the stokes parameters versus time and can control and adjust the measurement parameters such as samples and averaging time.
This example shows that the IPM5300 precisely and accurately measures fast changes of the States of Polarization (SOP).
An example of the measurement capability of the IPM5300 polarimeter is demonstrated in the data shown below. A system, shown above, was set up to demonstrate the capabilities of the IPM5300. A fiber pigtailed laser was used as the input to the polarization controller. The signal from the controller was fed to the IPM5300 that was installed in a TXP chassis, which was controlled via a local computer. The acquired data included the state of polarization (SOP), the change in SOP, the power and DOP. This data is shown in Figures 1 and 2. The polarization controller (e.g. Thorlabs DPC5500), a piezoelectric based controller, was controlled with a square wave signal at 2kHz to cause quick changes in the state of polarization into the polarimeter. The induced polarization change was 82° on the Poincaré sphere.
Figure 1a shows the measured Stokes vector elements (S1, S2 and S3), while Figure 1b shows the angular deviation in the state of polarization on the Poincaré sphere. Figure 2 shows the total measured power and the DOP versus time. One aspect of the data that is clearly evident in Figure 1 is the ripple. The polarimeter, at 1 million samples per second, accurately measures the SOP as the controller changes polarization (Figure 1a). The ripple in the data has a period of 20µsec (50kHz), which is easily resolved by the polarimeter. This ripple is real variations in SOP caused by effects of variations in the mechanical stress on the fiber due to a 50kHz mechanical resonance in the piezo controller. Despite the resonance, the measured optical power and DOP was constant as the polarization was changed. The deviations in the data are at the measurement uncertainties of the polarimeter, < 0.02 dB and < 0.1% respectively.
The following data was taken using a standard piezoelectric polarization controller to change the input SOP to the IPM5300 from one state to another. The ripple in the data is due to mechanical resonance in the piezo elements.
The data below was captured simultaneously with the data in the plots above.
|1||Trigger||I||3.3/5 V||External Trigger-signal (0V=L, 3.3 ... 5 V=H) (for array mode)|
|3||DOP||O||-2.5 ... +2.5 V||Degree of Polarization (0 ... 125%) (-2.5 V= 0%, 0 V= 62.5%, +1.5 V= 100%)|
|4||S2||O||-2.5 ... +2.5 V||Normalized Stokes Vector S2 (-1 ... +1)|
|5||Power||O||-2.5 ... +2.5 V||Optical Power log. (-30 ... +20 dBm) (0V = -5 dBm)|
|6||DGND||Digital ground for Trigger|
|7||Analog In||I||0 ... +2.5 V||Analog Control signal (not used here)|
|8||S3||O||-2.5 ... +2.5 V||Normalized Stokes Vector S3 (-1 ... +1)|
|9||S1||O||-2.5 ... +2.5 V||Normalized Stokes Vector S1 (-1 ... +1)|
The Software Package for the TXP5000 Platform contains the Software Modules for the IPM5300
The available software is organized into the following categories:
|x||x||In-line Polarimeter Module for TXP5000 (IPM5300)|
|x||TXP 4 Slot Chassis with USB Control (TXP5004)|
|x||Preconfigured Laptop with Software & GUI Installed|
|x||USB Connection Cable|
|x||x||Software CD ROM|
|x||x||LabVIEW™ and LabWINDOWS™ /CVI Driver Set|
In-line Polarimeter Module for TXP5000 (Without Chassis & PC)
Benchtop In-line Polarimeter IPM5300 incl. TXP5004 Chassis & PC