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US 5,018,857 AGranted
Passive ring resonator gyro with polarization rotating ring path
AssigneeHoneywell Inc.
InventorsGlen A. Sanders, Robert B. Smith, Gordon F. Rouse
Life of this patent
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Abstract
A passive ring resonator gyro is constructed of an electromagnetic waveguide ring path which causes a specified rotation of the polarization of the waves, once for each round trip through the ring path. For an optical fiber ring path, a splice at some point is introduced in the ring path in which the fiber ends are rotated relative to each other in order to effect polarization rotation.
Claims21
A ring resonator gyro comprising:
- a ring resonator including, at least in part, a birefringent waveguide portion having principal axes of birefringence, and in which at some selected point along said birefringent waveguide, said principal axes of birefringence are rotated by a selected angle about the axis of propagation direction of said waveguide;
- first means for producing first and second electromagnetic waves outside said ring resonator;
- and
- coupling means for
- coupling a first portion of said first electromagnetic wave into said ring resonator to propagate in a first direction along said axis of propagation direction of said waveguide, and
- coupling a first portion of said second electromagnetic wave into said ring resonator to propagate in a second direction along said axis of propagation direction of said waveguide opposite said first direction.
3 more elements
A ring resonator gyro comprising:
- a ring resonator including, at least in part, an electromagnetic polarization maintaining waveguide portion having linear birefringent characteristics which define first and second polarization axes perpendicular to the axis of propagation direction of said waveguide;
- first means for producing first and second electromagnetic waves outside said ring resonator;
- coupling means for
- (i) coupling a first portion of said first electromagnetic wave into said ring resonator to propagate in a first direction along said ring resonator, and in which said coupled first portion of said first electromagnetic wave results in the propagation of first and second polarized waves in said first direction due to, at least in part, said birefringence characteristics of said waveguide portion, and
- (ii) coupling a first portion of said second electromagnetic wave into said ring resonator to propagate along said ring resonator in a second direction opposite said first direction, and in which said coupled first portion of said first electromagnetic wave results in the propagation of third and fourth polarized waves in said first direction due to, at least in part, said birefringence characteristics of said waveguide portion, and said ring resonator includes means for causing
- (i) the free spectral range of resonant frequencies of said first polarized waves to be substantially equal to the free spectral range of the resonator frequencies of said second polarized waves, and
- (ii) each of the resonant frequencies of said second polarized waves to be substantially equally separated from adjacent resonant frequencies of said first polarized waves,
- (iii) the free spectral range of resonant frequencies of said third polarized waves to be substantially equal to the free spectral range of the resonant frequencies of said fourth polarized waves, and
- (iv) each of the resonant frequencies of said fourth polarized waves to be substantially equally separated from adjacent resonant frequencies of said third polarized waves.
6 more elements
A ring resonator gyro comprising:
- a ring resonator including, at least in part, an electromagnetic polarization maintaining waveguide portion having linear birefringent characteristics which define first and second polarization axes along the propagation direction of said waveguide;
- first means for producing first and second electromagnetic waves outside said ring resonator;
- coupling means for
- coupling a first portion of said first electromagnetic wave into said ring resonator to propagate in a first direction along said ring resonator, and
- coupling a first portion of said second electromagnetic wave into said ring resonator to propagate along said ring resonator in a second direction opposite said first direction;
- second means for spatially rotating, by a selected angle, the direction of linear polarization of said first portions of said first and second electromagnetic waves relative to the axis of propagation of said waveguide for each round trip through said ring resonator.
3 more elements
A ring resonator gyro comprising:
- a ring resonator including, at least in part, an electromagnetic polarization maintaining waveguide portion having linear birefringent characteristics which define first and second polarization axes perpendicular to the axis of propagation direction of said waveguide, and in which said birefringent characteristics are defined substantially by first and second indexes of refraction of said waveguide portion;
- first means for producing first and second electromagnetic waves outside said ring resonator;
- coupling means for
- (i) coupling a first portion of said first electromagnetic wave into said ring resonator to propagate in a first direction along said ring resonator, and in which said coupled first portion of said first electromagnetic wave results in the propagation of first and second polarized waves in said first direction due to, at least in part, said birefringence characteristics of said waveguide portion, and
- (ii) coupling a first portion of said second electromagnetic wave into said ring resonator to propagate along said ring resonator in a second direction opposite said first direction, and in which said coupled first portion of said first electromagnetic wave results in the propagation of third and fourth polarized waves in said first direction due to, at least in part, said birefringence characteristics of said waveguide portion;
- and
- said ring resonator includes
- means for causing said first and second polarized waves to exhibit resonant frequencies having substantially equal free spectral range which is substantially a function of an average of said first and second indexes of refraction, and
- means for causing said third and fourth polarized waves to exhibit resonant frequencies having substantially an equal free spectral range which is substantially a function of an average of said first and second indexes of refraction.
6 more elements
Dependencies are inferred from the claim text.