Patent ID: 7548572

Claim:
A laser gyro comprising: an optical ring cavity including at least three mirrors, a solid-state amplifying medium and a feedback system, the cavity and the amplifying medium being such that only two counterpropagating optical modes can propagate in opposite directions at the same time one with respect to the other inside said optical cavity, the feedback system allowing the intensity of the two counterpropagating modes to be kept almost the same, the feedback system comprising, inside the cavity, an optical assembly including: a polarizing element, a device exhibiting a nonreciprocal effect that acts on the polarization state of the counterpropagating modes, that consists of a material exhibiting the Faraday effect and that is polarized by a permanent magnet, a device exhibiting a reciprocal effect that also acts on the polarization state of the counterpropagating modes, and wherein the feedback system comprises control means for adjusting the reciprocal effect of the device exhibiting a reciprocal effect.