
Regeneration Laser Station
Turn-key industry-grade solution for optical frequency transfer over optical fibers
Exail proposes all the hardware and software to enable long-haul optical frequency dissemination over optical fibers. Regeneration Laser Stations and bi-directional optical amplifiers are cascaded along an optical fiber to cover distances as long as thousands of kilometers while preserving the frequency stability provided by the best optical clocks in the world. Our technology was designed to transfer the metrological optical reference signal on a dark channel of the DWDM spectrum in parallel of Internet data traffic, but it can also work on a dark fiber. Exail offers the world’s only industry-grade solution at this level of performance.

The supervision tool
Exail’s solution for optical frequency transfer can be deployed within a few days and has shown to provide uptimes as high as 99 % over a week. This is enabled by the remote and automated operation of the hardware supervised by a global supervision tool. The supervision tool is composed of:
A supervision software: to monitor and control the REFIMEVE+ performances
A database: store all the information useful to the network management
A human-machine interface: for end users, academic teams and the telecom network manager
- Monitoring the proper functioning and remotely control the equipment parameters in real-time.
- Detecting and managing bugs and alarms (cycle slips, polarization optimizations, …)
- Uploading the information collected on the field and store in the database (alarm, events, …)
- Administrating and troubleshooting system configurations
- Pre-processing data: outliers detection, Allan Deviation calculation, …
The supervision software is in charge of
The supervision tool of the REFIMEVE+ network currently monitors more than 150 pieces of equipment (EDFA, RLS, frequency counters). It enables the secured full remote access to all the equipment (RLS, ES, UM, EDFA) via the hosting telecom network infrastructure.
- Fully secured communication for supervision protocol: SSH, SNMP
- Supervision tool deployable through usual internet connection
- User-friendly webapp interfaces
- Remote access and real-time data retrieval
Key features
Specifications
Typical performances
The Regeneration Laser Station (RLS) is a stand-alone system that actively compensates the phase noise introduced by the fiber links and provides an ultra-stable output laser in the ITU channel 44 (1542.14 nm, other wavelengths available on demand). It enables also to cascade fiber links in order to set-up long-distance frequency dissemination. It has been designed to be installed in a Telecom network nodes in respect to NF/EN 60950-1 and NF/EN 60825-1 norms. It can work both on a dark channel and on a dark fiber.

Fig. 1: Fractional frequency instability calculated from data recorded with Λ-counter and 1 s gate time versus averaging time. Dark red squares, modified Allan deviation for a compensated 200 km laboratory link; light red circles, modified Allan deviation for the free-running 200 km laboratory link; dark green stars, modified Allan deviation for a short link to estimate the noise floor of the RLS; light green diamonds, modified Allan deviation for the free-running short link.
Fig 2: End-to-end phase fluctuations after propagation over a 680 km fiber link. Data from F. Guillou-Camago et al., « First industrial-grade coherent fiber link for optical frequency standard dissemination», Applied Optics, Vol. 57, No. 25 (2018)
Central wavelength | 1542 nm (ITU Channel 44) |
---|---|
RLS NOISE FLOOR | |
Relative short term frequency stability | < 3×10-17 @1 s |
Relative long term frequency stability (noise floor) | < 2×10-20 @103 s |
Typical accuracy of fiber link | < 1e-19, depending on link characteristics |
Temperature sensitivity of the interferometer | < 1 fs / °C |
Typical maximum range between 2 RLS on standard telecom fiber links | 500 km |
PHYSICS PACKAGE | |
MASS AND DIMENSIONS | |
Number of boxes | 2 |
Mass | 16.7 kg for the RLS 4 kg for power supply |
Dimensions | 5U 19’’ rack for the RLS 2U 19’’ rack for the power supply unit |
ELECTRICAL RATINGS | |
Supply voltage | 100-240 Vac |
Frequency | 50-60 Hz |
Power | <110 W |
Current | 2A |
OPTICAL RATINGS | |
Class | 3R |
Output power | <3 dBm |
Input power | -60 dBm < P < 3 dBm |
Wavelength | 1542 nm + custom |
Regime | CW |
SYSTEM INTERFACE & CONTROL | |
Optical connectors | FC/APC |
Communication connectors | RJ45 |
Communication protocol | SSH, SNMP |
Degree of Ingress Protection | IP 30 |
ENVIRONMENTAL & PHYSICAL SPECIFICATIONS | |
Operating temperature | [15 ; 35] °C |
Storage temperature | [5 ; 30] °C |
Humidity | Maximum relative humidity 80 % for temperatures up to 31 °C decreasing linearly to 50 % relative humidity at 40 °C |