FREQUENCY-DOMAIN DETECTION OF COHERENCE MULTIPLEXED SENSOR SIGNALS BYUSING AN OPTICAL LOOP WITH A FREQUENCY SHIFTER

We describe a frequency domain detection scheme of coherence multiplex ed sensor signals by using an optical loop with a frequency shifter, T he optical path differences of the sensors are adjusted to integer-mul tiple of the loop length of the optical loop, and then the the sensor signals are multiplexed in the frequency domain, appearing at the inte ger-multiple of the working frequency of the frequency shifter, In the experiment, four Michelson-type sensors are successfully multiplexed with the sensitivities of about 2 mrad root Hz. The sensitivities are also theoretically calculated which are in good agreement with the exp erimental results, The optimum design of the optical loop is also disc ussed.