Demodulators For Optical Fiber Interferometers With [3 x3] Outputs

Abstract

A highly sensitive optical fiber interferometer sensor comprising a laser light source, a [2 X 2] optical fiber coupler to split the beam in two, a differential transducer which converts a signal of interest into optical phase shift in the laser light transmitted through the two optical fibers in the interferometer and a [3 X 3] optical fiber complex which recombines the two beams, producing interference which can be electronically detected. The use of the [3 X 3] coupler permits Passive Homodyne demodulation of the phase-modulated signals provided by the interferometer without feedback control or modulation of the laser itself and without requiring the use of electronics within the interferometer