System for suppression of relative intensity noise in a fiber optic gyroscope

A feedback loop for reducing light intensity fluctuations in a fiber optic gyroscope utilizing a light source, the feedback loop comprising:

• a modulator for generating an intensity modulated light by modulating light emitted from said light source;
• a tap coupler, operatively connected to said modulator, for receiving said intensity modulated light and sampling a part thereof to provide a sampled signal;
• a photodetector, operatively connected to said tap coupler, for sensing said sampled signal as a current and converting said sampled signal to a detected signal having a voltage proportional to said current;
• and
• servo control logic, operatively connected between said photodetector and said modulator, and responsive to said detected signal, for producing an error signal to cause said modulator to control the intensity of said light received from said light source by canceling out the intensity fluctuations of the light in said feedback loop.

A method for suppression of relative intensity noise in a fiber optic gyroscope utilizing a light source, the method comprising the steps of:

• receiving light emitted from said light source and sampling a part of the light to provide a sampled signal;
• sensing said sampled signal to provide a control signal representing an intensity of the light;
• and
• varying said intensity of the light received from said light source, in response to said control signal, to cancel out intensity fluctuations of the light and thereby suppress said relative intensity noise;
• and
• amplifying said control signal to produce an error signal;
• wherein the step of varying said intensity of the light includes modulating the intensity of the light received from said light source in accordance with said error signal, and wherein said intensity of said light is modulated at a rate responsive to variations in said error signal up to a frequency of at least 800 kilohertz.

A servo system for suppression of relative intensity noise in a fiber optic gyroscope using a light source, the system comprising:

• modulating means for generating an intensity modulated light by modulating the light received from said light source;
• sampling means for receiving said intensity modulated light to produce a sampled signal;
• detecting means for sensing said sampled signal and converting said sampled signal to a control signal proportional to an intensity of the light received;
• and
• servo control means, responsive to said control signal, for producing an error signal to cause said modulating means to cancel out intensity fluctuations of said light received from said light source, thereby causing suppression of said relative intensity noise, wherein said servo control means is a voltage amplifier having a bandwidth of at least 800 kilohertz, and wherein said modulating means is capable of modulating said light at a rate responsive to variations in said error signal up to a frequency of at least 800 kilohertz.