Techniques for increasing round trip path length through an optical resonator coil without substantially increasing optical resonator coil size

A method for decreasing free spectral range in an optical resonator, the method comprising:

• optically coupling a portion of an optical signal to a first winding optical waveguide of a resonator coil including at least two winding optical waveguides;
• propagating the portion of the optical signal around at least a part of the first winding optical waveguide;
• optically coupling a portion of the portion of the optical signal from the first winding optical waveguide to a second winding optical waveguide of the resonator coil;
• propagating the portion of the portion of the optical signal around at least a part of the second winding optical waveguide;
• and
• optically coupling a portion of the portion of the portion of the optical signal from the second winding optical waveguide to the first winding optical waveguide.

An optical gyroscope comprising:

• an optical source comprising at least one laser and configured to emit at least one optical signal;
• an optical resonator comprising a rotation axis around which the optical gyroscope is configured to rotate;
• opto-electronic circuitry comprises at least one optical detector and is configured to receive the at least one optical signal, to optically couple to the optical resonator a gyroscope portion of each of the at least one optical signal, and to receive at least one gyroscope optical signal each of which is derived from the gyroscope portion;
• wherein the opto-electronic circuitry is further configured to generate, using the at least one gyroscope optical signal, an electronic signal representative of a parameter from which a rate of rotation of the optical gyroscope around the rotation axis;
• and
• processing circuitry electrically coupled to the opto-electronic circuitry and configured to receive the electronic signal and to determine the rate of rotation of the optical gyroscope around the rotation axis using the electronic signal;
• wherein the optical resonator comprises:
• a first optical waveguide comprising a first input/output port and a first surface;
• a second optical waveguide comprising a second input/output port and a second surface;
• wherein at least one of the first and the second input/output ports is configured to receive each of the gyroscope portion of each of the at least one optical signal, and wherein at least one of the first and the second input/output ports is configured to emit each of the at least one gyroscope optical signal;
• a resonator coil of optical waveguide comprising a first winding optical waveguide comprising a first waveguide port, a second waveguide port, a third surface adjacent and opposite to the first surface, and a fourth surface adjacent and opposite to the second surface, a second winding optical waveguide comprising a third waveguide port and a fourth waveguide port, and a first optical coupler comprising a first coupler port, a second coupler port, a third coupler port, and a fourth coupler port;
• and
• wherein the second winding optical waveguide is within a first region surrounded at least in part by the first winding optical waveguide;
• wherein the first waveguide port is optically coupled to the first coupler port, wherein the second waveguide port is optically coupled to the fourth waveguide port, wherein the third waveguide port is optically coupled to the third coupler port, and wherein the fourth waveguide port is optically coupled to the fourth coupler port;
• wherein the first optical coupler is configured to optically couple optical energy between the first and the second coupler ports and between the third and the fourth coupler port;
• wherein the first optical coupler is inserted anywhere in and around the first winding optical waveguide except for where the third surface is adjacent and opposite to the first surface, and where the fourth surface where is adjacent and opposite to the second surface.