Experimental tests of a wavemeter based on phi-OTDR with thermally stabilized weak FBGs

We present experimental results of continuous wavelength measurements for narrow linewidth laser in C -band. Designed setup is based on a phi-OTDR scheme and can be added as a module of DAS system for laser frequency drift measurement and compensation. Wavemeter uses multi-base Fizeau interferometers with passive or active thermal stabilization. They are realized on weak fiber Bragg gratings (wFBGs) inscribed in single fiber line located in compact thermostat. Achieved accuracy of setup was about 100 fm with 1 kHz discretization frequency. Possible improvements can allow reaching about 10 fm accuracy with more than 10 kHz sampling frequency.