Exail header regeneration laser stations rls

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.

Exail regeneration laser station fond blanc

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

  • The supervision software is in charge of

    • 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 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.

    Key features

    • 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

    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.

Exail typical perf regeneration laser station

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)
(other wavelengths in option)

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
(485 mm x 222 mm x 540 mm)

2U 19’’ rack for the power supply unit
(485 mm x 90 mm x 250 mm)

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