Patent ID: 9019482
Filing Date: 2015-04-28
Classification: G01D,G01J,G01K,G01L,G02B

Abstract:
1. An optical device comprising: a fiber Bragg grating comprising a substantially periodic refractive index modulation along a length of the fiber Bragg grating, wherein the fiber Bragg grating has a power transmission spectrum comprising a plurality of local transmission minima comprising a first local transmission minimum comprising a Bragg wavelength of the fiber Bragg grating, a second local transmission minimum on a short wavelength side of the Bragg wavelength, and a third local transmission minimum on a long wavelength side of the Bragg wavelength; a narrowband optical source of at or in the vicinity of a local transmission maximum between a pair of neighboring local transmission minima of the plurality of local transmission minima, the local transmission maximum having a maximum power at a transmission peak wavelength; at least one optical detector in optical communication with the fiber Bragg grating; at least one coupler in optical communication with the narrowband light source, wherein, during operation of the optical device, the at least one coupler splits the light from the narrowband optical source into a first portion having the wavelength and propagating along a first optical path extending along and through the length of the fiber Bragg grating to the at least one optical detector and into a second portion having the wavelength and propagating along a second optical path different from the first optical path; a fiber loop, wherein at least a portion of the fiber loop comprises the fiber Bragg grating, wherein the first optical path extends in a first direction along the fiber loop and the second optical path extends in a second direction along the fiber loop, the second direction opposite to the first direction; and wherein the at least one coupler is optically coupled to the narrowband optical source and the fiber loop, wherein, during operation of the optical device, the first portion and the second portion are recombined by the at least one coupler after propagating along and through the length of the fiber Bragg grating, wherein the at least one optical detector comprises a detector of changing optical phase of the recombined first and second portions resulting from a phase difference between the first portion and the second portion due to perturbation of the fiber Bragg grating.