Bicell fiber optics homodyne phase demodulator — Experimental results

In the paper we present a novel experimental approach to the signals demodulation by using the optical interferometer operates in homodyne mode. Real time analysis of Young interference fringes is proposed to obtain an extremely high resolution of phase changes. A phase modulation effect in a signal arm of interferometer is observed as a shift of the interference fringes. A simple arithmetic combination of signals from B-PD placed in a fringe pattern plane is only one necessary numerical manipulation to obtain exactly a phase difference Δφ. Concept of signals demodulation in the Fourier focal plane can be only used for exactly defined geometrical (B-PD and Young interferometer geometry) and physical parameters (polarization, wavelength). We demonstrate the individual demodulator characteristics which depend on all geometrical and physical parameters. In the paper we explain how to optimize the setup geometry to obtain an extremely high resolution of measurement in (-π, π) range of detected phase.