Er-Doped Ultra-Low Phase Noise Optical Frequency Comb

  • Accurately Measures Optical Frequencies
  • Low Phase Noise of <80 mrad over the Entire Spectrum
    (1 Hz to 2 MHz)
  • Stability of 5 x 10-18 in 1 s and 5 x 10-19 in 1000 s
  • Extension for 500 - 1050 nm or 1050 - 2100 nm
    Spectral Range Available
  • 250 MHz Comb Spacing


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Menlo Systems' Ultra-Low-Noise Frequency Comb


  • Turnkey Metrology System; Fully Automated and Fully Fiber-Coupled
  • Includes All Needed Optics and Electronics:
    • Oscillator with PM Output
    • Amplifier for Octave Generation and Fiber-Coupled All-PM f:2f Interferometer
    • Control Units
    • Phase-Locked Loops
    • Displays
    • Software and Data Acquisition
  • High Repetition Rate
  • Extension Packages Available from 500 nm to 2100 nm
  • Designed for Continuous High-Bandwidth Laser Locking
  • Low Phase Noise of <80 mrad (1 Hz - 2 MHz) over the Entire Spectrum
  • High Stability of 5 x 10-18 in 1 s and 5 x 10-19 in 1000 s
  • High-Bandwidth >1 MHz Actuators for Both Carrier Envelope Offset Beat and Repetition Rate
  • Continuous Offset Frequency Tuning Possible

Frequency comb technology makes direct measurement of absolute, SI-referenced, optical frequencies possible with utmost accuracy. As one can derive time and length from frequency measurements, these precise tools vastly simplify metrology and enable new directions in physics.

The femtosecond laser is ready to use at the press of a single button, and automatic phase-lock loops ensure easy stabilization to either an RF or an optical reference. Due to the mature system design including several combined actuators, long-term operation on the order of weeks, without adjustment, is possible. With the M-VIS and M-NIR Extension Packages, the system is capable of providing a source for frequency metrology in both the visible (500-1050 nm) and the near-IR regions (1050-2100 nm) of the spectrum simultaneously. A wide range of optional features enables us to tailor these versatile systems for customer-specific solutions.

The FC1500-ULNPLUS Ultra Low Noise Optical Frequency Comb provides system performance and frequency stability between two or more user-defined frequencies at the 10-19 level. This exceeds the stability of any optical oscillator demonstrated to date, and can be relevant for applications such as optical clocks in quantum sensing and fundamental physics. Our all polarization maintaining figure 9® mode locking technology, together with high bandwidth actuators (>1 MHz) for both the carrier-envelope offset frequency and the repetition rate guarantee high performance.


  • Optical (Lattice) Clocks
  • Transfer of CW Laser Stability of Full Comb Spectrum from 500 nm to 2 µm
  • Optical Clock Comparison (via Fiber Network)
  • Broadband High Resolution Spectroscopy
  • Precision Radio Frequency Generation
  • Laser Stabilization to Optical References
Simon Kocur
Simon Kocur
Menlo Systems
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Please note that these Optical Frequency Combs are available directly from Menlo Systems, Inc. within the United States and from Menlo Systems GmbH outside the United States.
United States
Phone: +1-973-300-4490
Outside United States
Phone: +49-89-189166-0
Item #  FC1500-ULNPLUS
Comb Spacing 250 MHz
Accuracy 1 x 10-18 for τ > 100 s (a)
Stability 5 x 10-18 in 1 s (a,b), 5 x 10-19 in 1000 s (a,b)
Integrated Phase Noise <80 mrad [1 Hz - 2 MHz]
Line Width <1 Hz (a,c)
Tuning Range of Spacing Between Individual Comb Lines >4 MHz
Tuning Range of CEO Frequency >250 MHz
Laser Outputs Five Fiber-Coupled, Linearly Polarized PM Output Ports
Center Wavelength 1560 nm
Spectral Range >25 nm
(500 - 1050 nm with M-VIS, 1050 - 2100 nm with M-NIR)
Average Output Power >10 mW From Each Laser Port (>100 mW with M-VIS, >200 mW with
CW Laser Inputs Approx. 1 mW Optical Power Required, Wavelength User-Defined in the nm Range (More Upon Request)
  1. Phase Lock to Optical Reference
  2. Modified Allan Deviation (λ-Type Counter, Timebase 1 ms)
  3. Limited by Resolution of Bandwidth Analyzer
Requirements  FC1500-ULNPLUS
Input Requirements CW Optical Reference, Power Level Approx.1 mW (See Menlo ORS Datasheet)
10 MHz Frequency Reference, Power Level +7 dBm
Operating Voltage 100/115/230 VAC
Frequency 50 to 60 Hz
Power Consumption <500 W, <3 kW Including Chiller
Cooling Requirements Closed Cycle Chiller Included
Operating Temperature 22 ± 5 °C
Optical Unit Dimensions / Weight 706 x 716 mm / Approx. 80 kga
Control Unit Dimensions / Weight 600 x 800 mm / Approx.140 kga 
    • Standard System Configuration

3-Channel Piezo Controller
Click to Enlarge
FC1500-ULNplus Phase Noise
Analysis of the out-of-loop beat signal between two combs at the strontium clock transition frequency. The extremely low phase noise proves that the spectral purity is transferred to the target wavelength.

Menlo System Optical Frequency Combs are complete solutions. The modular system architecture allows for easy additions of more functionality to an existing system. Multiple extensions can be combined in a system.

M-NIR Extension Package
Extends the stabilized comb spectrum to a range of 1050 - 2100 nm with free-space output port and >200 mW average power. The measurement port can be optimized independently from the CEO frequency stabilization.

M-VIS: Extension Package
Extends the stabilized comb spectrum to the 500 - 1050 nm range with a free-space output port and >60 mW average power.

HMP High Power Measuring Port
Provides stabilized comb light with highest power at customer-defined wavelengths for high precision measurement of lasers with low power levels (<100 µW). A minimum of 3 mW average power in a 3 nm window is provided at the central wavelength specified by customer. Available for 1050 - 2100 nm (HMP-NIR), or 525 - 1050 nm (HMP-VIS). The output is fiber coupled and optional available as free space.
For 390 - 400 nm (HMP-UV) a minimum of 1 mW average power in a 1 nm window is provided. The output is free space.

P250 PULSE-EDFA: Erbium-doped Fiber Amplifier
All polarization maintaining (PM) amplifier delivers intense near infrared pulses with >350 mW at 1560 nm. Several amplifiers can be added for multiple measurement ports.

M-780 High Power Measuring Port at 780 nm
Output provides stabilized comb light with highest power at 780 nm. Contains an amplifier and subsequent frequency conversion, delivering a minimum of 150 mW average power with a central wavalength in the range of 780-800 nm. The output is free space and optional available as fiber-coupled.

BDU: Beat Detection Unit
Generates and measures the beat signal between the frequency comb and an external continuous wave (CW) laser. Available for various spectral ranges, with free space or fiber-coupled optics, and matched to the customer's laser frequencies.

LLE-SYNCRO: Locking Electronics Unit
Allows locking of an external CW laser to the stabilized frequency comb. Performance has been field tested with lasers from major suppliers.

Microwave Ultrastable RF Output
Ultrastable RF output in the 1 MHz to 10 GHz range. Utilizing a high-sensitivity, high-speed photodetector and a frequency divider where needed.

GPS GPS-Based 10 MHz Frequency Reference
Provides the RF reference input signal for the frequency comb, combining the superior short-term stability of an ultrastable quartz oscillator with the long-term accuracy of the GPS.

WLM-VIS Integrated Wavelength Meter
Integrated wavelength meter with 100 MHz accuracy in the 500 - 1100 nm range.

WLM-NIR Integrated Wavelength Meter
Integrated wavelength meter with 100 MHz accuracy in the 900 - 1700 nm range.

ORS-DL Optical Reference System
The ORS-DL Optical Reference System consists of an external cavity diode laser locked to a stable high-finesse cavity made of ultra low expansion glass. It offers a very narrow linewidth (<1 Hz) and outstanding short-term stability (<2 x 10-15 Hz in 1 s) at wavelengths such as 657 nm, 689 nm, 698 nm, 729 nm, and many others from 400 nm to 1650 nm. By locking the FC1500-250-ULN to the ORS-DL, the purity of this state-of-the-art optical reference can be transferred throughout the entire frequency comb spectrum.

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Optical Frequency Comb

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FC1500-ULNPLUS Support Documentation
FC1500-ULNPLUSNEW!Ultra Low Noise Optical Frequency Comb, 250 MHz
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