US 12,352,618 B2
Demodulation of fiber optic sensors
Ming Han, Okemos, MI (US)
Assigned to Board of Trustees of Michigan State University, East Lansing, MI (US)
Filed by Board of Trustees of Michigan State University, East Lansing, MI (US)
Filed on Mar. 23, 2022, as Appl. No. 17/702,130.
Claims priority of provisional application 63/173,831, filed on Apr. 12, 2021.
Prior Publication US 2022/0326069 A1, Oct. 13, 2022
Int. Cl. H01H 9/00 (2006.01); G01D 5/353 (2006.01); G01H 9/00 (2006.01); G02B 6/42 (2006.01); H04B 10/564 (2013.01); H04J 14/02 (2006.01); H04B 10/50 (2013.01)
CPC G01H 9/004 (2013.01) [G01D 5/35306 (2013.01); G02B 6/4215 (2013.01); H04B 10/503 (2013.01); H04B 10/564 (2013.01)] 26 Claims
OG exemplary drawing
 
1. A sensor system comprising:
an optical fiber;
a laser configured to emit a laser beam into the optical fiber;
a phase modulator, coupled to the optical fiber, configured to receive the laser beam;
a sensor configured to receive the laser beam from the phase modulator, the sensor comprising a coiled portion of the optical fiber with at least two gratings located on opposite uncoiled segments adjacent the coiled portion of the optical fiber;
a photodetector configured to receive a reflected portion of the laser beam from the sensor;
a splitter configured to receive an output from the photodetector and divide the output into a first route and a second route;
a first filter configured to receive a portion of the first route and output a first sub-output and at least a second sub-output;
a second filter configured to receive a portion of the first sub-output from the first filter and being configured to output a first term;
a first amplifier configured to receive a portion of the at least a second sub-output and being configured to obtain a second term;
a third filter configured to receive a portion of the second path and being configured to divide the second path into a third sub-output and at least a fourth sub-output;
a fourth filter configured to receive a portion of the third sub-output from the third filter and being configured to output a third term;
a second amplifier configured to receive a portion of the at least a fourth sub-output from the third filter and being configured to obtain a fourth term; and
a controller configured to receive the first term, the second term, the third term, and the fourth term in order to assist with sensing.