Importance

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Abstract

A quantum well bias mirror 30 provides phase modulation to two counter-propagating beams in a ring laser gyroscope so as to reduce or eliminate the effects of lock-in. The phase modulation is caused by inducing an index of refraction change, known as the Franz-Keldysh effect, in the quantum well bias mirror 30 by applying a varying electric field across a quantum well structure in the mirror 30. The quantum well bias mirror 30 is comprised of a substrate 32 coated with a plurality of dielectric layers 36,38 of alternately high and low refractive indices, respectively, which in turn are coated with a quantum well filter layer 34. The dielectric layers 36,38 are adjusted to provide maximum reflectivity of the counter-propagating beams. The quantum well filter layer 34 is adjusted to cause a reflection from its top surface when there is no electric field present and to cause a reflection from the top of the dielectric layers 36,38 when an electric field is present. The apparent disappearance of the quantum well filter layer 34 with the presence of an electric field acts to impart a differential phase shift between the two counter-propagating beams for establishing a frequency bias in the ring laser gyroscope, thereby reducing or eliminating the effects of lock-in.

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First Claim