Compact fiber optic gyroscope with feedback-enhanced frequency interferometry for precision measurement

A fiber optic gyroscope system, comprising:

• a broadband light source configured to transmit light waves;
• a first 50/50 directional coupler connected at an input port to the broadband light source, wherein the first 50/50 directional coupler is configured to split the light waves into a first path and a second path;
• a three port fiber circulator connected to the first 50/50 directional coupler, wherein the three port fiber circulator is configured to receive the light waves of the second path at a first port and emit the light waves of the second path from a second port;
• a second 50/50 directional coupler connected to the second port of the three port fiber circulator, wherein the second 50/50 directional coupler is configured split the light waves of the second path into a third path and a fourth path;
• an optical fiber coil connected to the second 50/50 directional coupler, wherein the optical fiber coil includes a plurality of loops configured to receive the light waves from the third path and the fourth path, circulate the light waves from the third path in a clockwise direction through the plurality of loops and circulate the light waves from the fourth path in a counterclockwise direction through the plurality of loops, wherein the light waves travelling in the counterclockwise direction are phase shifted with respect to the light waves travelling in the clockwise direction based on a rotational speed of the fiber optic gyroscope,
• wherein the second 50/50 directional coupler is configured to recombine the light waves travelling in the clockwise direction and the light waves travelling in the counterclockwise direction and transmit a set of recombined phase shifted light waves to the second port of the three port fiber circulator,
• wherein the three port fiber circulator is configured to emit a set of recombined phase shifted light waves from a third port, wherein the third port is connected to a feedback port of the first 50/50 directional coupler;
• an optical spectrum analyzer connected to the first path of the first 50/50 directional coupler, wherein the optical spectrum analyzer is configured to receive the set of recombined phase shifted light waves from the first path, apply frequency domain interferometry to the set of recombined phase shifted light waves and generate an interferogram of the set of recombined phase shifted light waves;
• a microprocessor including a circuitry, a memory storing program instructions and at least one processor configured to execute the program instructions to:
• perform a Fast Fourier Transform of the interferogram to transform the interferogram into a set of frequency components having repeated patterns;
• measure a spacing between two repeated patterns of frequency components;
• and
• determine, from the measured spacing, an angular speed of the fiber optic gyroscope.