Fiber-optic sensor array based on Sagnac interferometer with stable phase bias

We propose and experimentally demonstrate a novel fiber sensor array based on a Sagnac interferometer with very simple electronic signal processing. A stable quadrature phase bias was obtained using a phase modulator, and the polarization-induced signal fading was suppressed by using a depolarizer and a broad-band source. A phase sensitivity of about 4.0 μrad/sub rms///spl radic/Hz at 5 kHz was obtained using a two-sensor array.