Ring laser magnetic bias mirror compensated for non-reciprocal loss

Claim 2

A ring laser comprising means forming a closed loop optical cavity containing an active lasing medium for providing contradirectional light beams propagating along a closed loop circulatory path in the optical cavity, said optical cavity forming means being constructed, at least in part, of a frequency biasing light reflective multilayer member for imparting a differential phase shift to the contradirectional beams, said multilayer member including a magnetizable layer coated with at least one dielectric layer which has a thickness determined in accordance with the refractive index of the dielectric layer and wavelength and angle of incidence of the contradirectional beams on the multilayer member for substantially eliminating differential reflection of the contradirectional beams normally occurring at the multilayer member from the presence of the magnetizable layer while preserving non-reciprocal phase shift caused thereby.

Claim 3

The apparatus of claim 1 wherein the magnetizable layer is constructed of a magnetically saturable material.

Claim 4

The apparatus of claim 1 wherein the magnetizable layer is magnetized in a direction normal to the plane of incidence of the contradirectional beams impinging on the multilayer member and the beams are plane polarized parallel to the plane of incidence.

Claim 5

The apparatus of claim 1 wherein the optical cavity has a planar configiration, the contradirectional waves incident on the light reflective multilayer member are plane polarized parallel to the ring plane, and the magnetizable layer is magnitized in a direction normal to the ring plane.

Claim 6

The apparatus of claim 1 wherein the respective layers are arranged so that the contradirectional beams incident on the light reflective multilayer member first strike the dielectric and propagate therethrough to impinge on the magnetizable layer.

Claim 7

The apparatus of claim 5 wherein the magnetizable layer has a thickness determined in accordance with its light absorption characteristic such that light which is not reflected from the magnetizable layer surface region adjacent the dielectric layer is substantially absorbed in the course of propagating through the magnetizable layer.

Claim 8

The apparatus of claim 6 wherein the ring laser cavity has a planar configuration, the contradIrectional waves incident on the light reflective multilayer member are plane polarized parallel to the plane of the ring, and the magnetizable layer is magnetized normal to the ring plane.

Claim 9

The apparatus of claim 1 including a plurality of additional dielectric layers coated one on another over said dielectric layer, each additional dielectric layer having a phase thickness of approximately 180* for the total forward and back pathlength therethrough of contradirectional beams of predetermined wavelength and propagational direction.

Claim 10

A ring laser comprising means forming a closed loop optical cavity containing an active lasing medium for providing contradirectional light beams propagating along a closed loop circulatory path in the optical cavity and plane polarized parallel to the plane of incidence of the beams on a light reflective multilayer frequency biasing member which constitutes a part of said optical cavity forming means for imparting non-reciprocal phase shift to the beams, said light reflective multilayer member comprising a magnetic layer magnetized in a direction normal to the plane of incidence of the contradirectional beams impinging thereon and a plurality of dielectric layers of alternately high and low refractive index coated one on another over the magnetic layer, the dielectric layer adjacent the magnetic layer having a thickness determined in accordance with the refractive index of said adjacent dielectric layer and the wavelength of the beams and the incidence angle thereof on the light reflective multilayer member so as to substantially eliminate non-reciprocal losses normally occurring at the multilayer member from the presence of the magnetic layer while preserving non-reciprocal phase shift produced thereby, and the remaining dielectric layers each having a phase thickness of approximately 180* for the total forward and back pathlength of the contradirectional beams traveling therethrough to enhance the absolute reflection of the light reflective multilayer member.

Claim 11

A ring laser comprising means forming a closed loop optical cavity containing an active lasing medium for providing contradirectional light beams propagating along a closed loop circulatory path in the optical cavity and plane polarized parallel to the plane of incidence of the beams on a light reflective multilayer frequency biasing member which constitutes a part of said optical cavity forming means for imparting non-reciprocal phase shift to the beams, said light reflective multilayer member comprising a magnetic layer magnetized in a direction normal to the plane of incidence of the contradirectional beams impinging thereon and a plurality of dielectric layers of alternately high and low refractive index coated one on another over the magnetic layer, the dielectric layer adjacent the magnetic layer having a thickness determined in accordance with the refractive index of said adjacent dielectric layer and the wavelength of the beams and the incidence angle thereof on the light reflective multilayer member so as to substantially eliminate non-reciprocal losses normally occurring at the multilayer member from the presence of the magnetic layer while preserving non-reciprocal phase shift produced thereby, and the remaining dielectric layers each having a phase thickness of approximately 180* for the total forward and back pathlength of the contradirectional beams traveling therethrough to enhance the absolute reflection of the light reflective multilayer member.

Claim 12

The apparatus of claim 9 wherein the magnetic and dielectric layers are so constructed and arranged that the contradirectional light beams incident on the light reflective multilayer member first strike the dielectric layers and propagate therethrough to the magnetic layer.

Claim 13

The apparatus of claim 10 wherein the thickness of the magnetic layer in the direction of beam propagation is such that only light reflected from the front surface and the region slightly in back of the adjacent dielectric layer, to the exclusion of light reflected from the opposite surface of the magnetic layer, is effective in producing non-reciprocal loss and phase effects.

Claim 14

The apparatus of claim 11 wherein the optical cavity has a planar configuration, the contradirectional waves incident on the light reflective multilayer member are plane polarized parallel to the plane of the ring, and the magnetization of the magnetic layer is oriented normal to the ring plane.

Claim 15

The apparatus of claim 12 wherein the magnetic layer is constructed of a magnetically saturable material.

Claim 16

The apparatus of claim 13 wherein the respective magnetic and dielectric layers each have a planar configuration.

Claim 17

The apparatus of claim 5 wherein the magnetizable layer is magnetized in a direction normal to the plane of incidence of the contradirectional beams impinging on the multilayer member and the beams are plane polarized parallel to the plane of incidence.