Influence of the coherence length of radiation on phase noise in a fiber-optic rotation sensor

An investigation was made of a fiber-optic rotation sensor with a semiconductor light source. The length of a single-mode fiber waveguide was 1 km, its linear losses were ~ 2 dB/km at λ = 0.84 μ, the coil diameter was 19 cm, and the sensitivity of the sensor was 0.5 deg/h (1.1 × 10^–5 rad) for an integration time of 0.5 sec. The drift of the zero setting in 80-min operation was ~ 6 deg/h when the fiber waveguide coil was screened from external magnetic fields and the integration time was 1 sec. A comparison was made with a similar rotation sensor based on a He–Ne laser. A new method for suppressing nonreciprocal phase noise by a vibration device simulating the Sagnac phase shift in a wide spectral range was proposed and demonstrated.