Optimization And Implementation Of Optical Phase Noise Compensation For Frequency Transfer Over Optical Fiber

With improvement of atomic frequency source’s stability, therequirement of the stability of frequency transfer system keeps increasing.Compared to the traditional satellite-based two-way frequency transfertechnique, the frequency transfer over optical fiber has advantages of highbandwidth, low loss, strong anti-interference, etc., which is now beenextensively studied and used for high-precision frequency source’s deliveryapplication.The phase noise arising from temperature and some other externalenvironmental changes brings great impacts on the stability of the frequencytransfer over optical fiber. In this paper, we design an active optical phasecompensation system for frequency transfer over optical fiber based onFPGA, temperature-controlled fiber delay line and PZT delay line. Atemperature-controlled fiber delay line with a large dynamic range and itsdrive circuits are designed and implemented. The tests are carried out in aRound-Trip based frequency transfer experimental system over20kmoptical fiber link. The result shows that a control precision of2.5ps and0.6ps can be reached by using a temperature-controlled fiber delay linewith a dynamic range of about21ns and4ns, respectively. And a controlprecision of1ps can be reached by using a4ns temperature-controlledfiber delay line in the system of100km frequency transfer. The frequency transfer system after the active phase noise compensation can achieve thestability of8×10-14per second and4×10-17for10000s when the dynamicrange of fiber delay line is4ns.The main work of this paper includes:（1） An overall hardware, software and the visual interface solutions forthe control unit of the active optical phase noise compensation are designedand implemented. Hardware solution is mainly the design andimplementation of electric circuits related to FPGA. Software solutionincludes design and implementation of FPGA-based system algorithms.PC-based visual interface is developed by LabVIEW.（2） We analyze the basic principle of TEC and the relationship betweenoptical delay line’s time variation and temperature change. Based on this, wedesign and implement a temperature-controlled fiber delay line with a largedynamic range and its driver circuits.（3） The performance of the designed temperature-controlled fiber delayline is experimentally investigated based on frequency transfer system. Andcarry out tests in a Round-Trip based frequency transfer experimentalsystem optical fiber link.We get the steady phase jitter as well as frequencytransfer stability of the transfer system。...