Apparatus and method for electronic RIN reduction in fiber-optic sensors utilizing filter with group delay

An optical sensor system for producing a sensor signal having reduced noise, comprising:

• an optical sensor adapted to receive a sensor input light and adapted to measure a physical quantity, with the optical sensor producing a sensor output signal corresponding to the physical quantity and a first noise component;
• a first detector which detects the sensor output signal;
• a second detector which detects the sensor input light corresponding to a second noise component;
• a high pass filter or DC block coupled to the second detector;
• a filter, with a group delay substantially corresponding to a time delay of the sensor input light traversing the optical sensor, coupled to the high pass filter or DC block,
• a multiplier, which multiplies the filtered time-delayed second noise component with the sensor output signal, and
• a subtractor which subtracts the multiplied filtered time-delayed second noise component from the sensor output signal to produce the sensor signal having the reduced noise.