Patent ID: 7130053

Claim:
A device for measuring a nonreciprocal effect, comprising optical components including: a light source; a first light splitter; a Sagnac ring having a first and a second branches: a second light splitter that divides an incident light into said first and second branches of the Sagnac ring; a nonpolarizing monomode spatial filter located between said first light splitter and said second light splitter; a light detector; said optical elements being so structured and arranged so that an incident light arriving at the first splitter and coming from the light source has a polarization state which is a combination of defined polarizations, said second splitter is a polarization splitter, to completely or partly split said incident light into a first and a second defined polarizations, a first portion of the light emitted by said light source can pass in succession through the first splitter, through the spatial filter, through the second splitter, to enter the first branch of the Sagnac ring and emerge via the second branch of the Sagnac ring, pass through the second splitter, through the spatial filter and through the first splitter and arrive at the light detector, a second portion of the light emitted by said light source can pass in succession through the first splitter, to the spatial filter, through the second splitter, to enter via the second branch of the Sagnac ring and emerge via the first branch of the Sagnac ring, pass through the second splitter, through the spatial filter and through the first splitter and arrive at the detector; wherein said first splitter is a partial polarization splitter structured so as to increase, as regards the polarization state of the light signal arriving at the light detector, the ratio of the polarization complementary to the polarization emitted by the source to the polarization emitted by the source and said light detector including a system for analyzing the polarization state of a light signal formed by the superposition of the first and second portions of the light arriving at the light detector.