Fiber-optic disturbance detection using combined Michelson and Mach-Zehnder interferometers

摘要

A fiber-optic sensor can have a Michelson sensor portion and a Mach-Zehnder sensor portion. A first splitter-coupler can be configured to split incoming light between a first fiber portion and a second fiber portion. A first polarization-phase conjugation device can be configured to conjugate a polarization phase of incident light corresponding to the first fiber portion, and a second polarization-phase conjugation device can be configured to conjugate a polarization phase of incident light corresponding to the second fiber portion. Each of the first and second polarization-phase conjugation devices can be configured to reflect light toward a detector and through the respective first and second fiber portions. A coupler can be configured to join light in the first fiber portion with light in the second fiber portion, and a third fiber portion can be configured to receive light from the coupler and to illuminate a second detector.

主权项

1. A method of detecting a disturbance using a passively terminated fiber optic sensor, the method comprising:
launching light into a fiber-optic sensor comprising (i) a first fiber portion and a second fiber portion defining a sensitive portion of the sensor, and a third fiber portion defining an insensitive portion of the sensor, each of the first, second and third fiber portions extending between respective proximal and distal ends, (ii) a first splitter-coupler positioned adjacent the proximal ends of the first fiber portion and the second fiber portion and configured to split incoming light between the first fiber portion and the second fiber portion via a third fiber coupler, (iii) a first coupler and second coupler position adjacent the respective distal ends of the first fiber portion and the second fiber portion and configured to combine light from the first fiber portion with light from the second fiber portion and to direct the combined light into the third fiber portion, and (iv) a first polarization-phase conjugation device configured to conjugate a polarization phase of incident light corresponding to the first fiber portion and a second polarization-phase conjugation device configured to conjugate a polarization phase of incident light corresponding to the second fiber portion; detecting with a first detector a combined first signal portion and a second signal portion from light reflected by the first polarization-phase conjugation device and light reflected by the second polarization-phase conjugation device; detecting with a second detector the combined first signal portion from light combined by the third fiber coupler and directed into the third fiber portion; and determining the location of a disturbance based on, at least in part, a comparison of the first signal portion and the second signal portion.