Patent ID: 7030992

Claim:
A fiber-optic interferometer, comprising: a first dual-mode optical fiber for receiving a light input and exciting a first spatial mode and a second spatial mode; a first modal processor connected to said first dual-mode optical fiber for selecting said first spatial mode and said second spatial mode; a second dual-mode optical fiber connected to said first modal processor for propagating said first spatial mode and said second spatial mode and producing a phase shift (Δφ) between said first spatial mode and said second spatial mode in response to an external perturbation effect; a second modal processor connected to said second dual-mode optical fiber for re-selecting said first spatial mode and said second spatial mode and producing a first light output interference pattern; and an analyzer having a polarization axis and connected to said second modal processor for adjusting said first light output interference pattern to produce a second light output interference pattern, so that said second light output interference pattern obtains an optimal contrast (C) through an adjustment of said polarization axis.