Demodulators for optical fiber interferometers with [3×3] outputs
A highly sensitive optical fiber interferometer sensor comprising a laser
light source, a [2×2] 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 [3×3] optical
fiber complex which recombines the two beams,
producing interference which can be electronically detected. The use of the
[3×3] 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.