Interrogator for a plurality of sensor fiber optic gratings

Abstract

An interrogator for a plurality of sensor fiber optic gratings. The interrogator includes an optical source for providing signals to the plurality of sensor fiber optic gratings. At least one optical filter converts optical signals, returned from the plurality of sensor fiber optic gratings, from (a) changes in peak reflection wavelength to (b) changes in intensity. At least one optical receiver receives the converted optical signals from the at least one optical filter.

What is claimed is: 
     
         1 . An interrogator for a plurality of sensor fiber optic gratings comprising:
 an optical source for providing signals to the plurality of sensor fiber optic gratings;   at least one optical filter converting optical signals, returned from the plurality of sensor fiber optic gratings, from (a) changes in peak reflection wavelength to (b) changes in intensity; and   at least one optical receiver receiving the converted optical signals from the at least one optical filter.   
     
     
         2 . The interrogator of  claim 1  wherein the optical source is a broadband optical source. 
     
     
         3 . The interrogator of  claim 2  wherein the broadband optical source is one of a light emitting diode (LED), a superluminescent light emitting diode (SLED), an amplified spontaneous emission (ASE) source and a semiconductor optical amplifier (SOA). 
     
     
         4 . The interrogator of  claim 1  further comprising at least one beam splitter directing output of the optical source to the plurality of sensor fiber optic gratings. 
     
     
         5 . The interrogator of  claim 4  wherein the at least one beam splitter receives optical signals returned from the plurality of sensor fiber optic gratings before the optical signals are received by the at least one optical filter. 
     
     
         6 . The interrogator of  claim 4  wherein the at least one beam splitter includes at least one of a fiber optic coupler and a fiber optic circulator. 
     
     
         7 . The interrogator of  claim 1  wherein the at least one optical filter is a linear filter. 
     
     
         8 . The interrogator of  claim 1  wherein the at least one optical filter includes a plurality of optical filters, and the at least one optical receiver includes a plurality of optical receivers such that each of the optical receivers is configured to receive signals from a corresponding one of the optical filters. 
     
     
         9 . The interrogator of  claim 1  wherein the at least one optical filter includes an optical add/drop multiplexer. 
     
     
         10 . The interrogator of  claim 1  further comprising a driver for pulsing the optical source. 
     
     
         11 . The interrogator of  claim 10  wherein the driver includes a modulator. 
     
     
         12 . The interrogator of  claim 11  wherein the driver provides randomization of intensity ripple phase versus wavelength. 
     
     
         13 . The interrogator of  claim 11  wherein the driver provides an injection current to the optical source that is varied sinusoidally. 
     
     
         14 . The interrogator of  claim 1  further comprising an amplifier associated with each at least one optical receiver. 
     
     
         15 . The interrogator of  claim 14  wherein the amplifier is a transimpedance amplifier. 
     
     
         16 . The interrogator of  claim 1  wherein the optical signals returned from the plurality of sensor fiber optic gratings signals are separated in time with a separation related to the physical separation of ones of the plurality of sensor fiber optic gratings. 
     
     
         17 . The interrogator of  claim 1  wherein the optical source is configured to be operated in a pulsed mode, and wherein an injection current received by the optical source is varied sinusoidally. 
     
     
         18 . The interrogator of  claim 17  wherein a sinusoidal variation of the injection current is less than 2%, and a period of the injection current is in a range of 0.1% to 1% of a sampling interval. 
     
     
         19 . The interrogator of  claim 1  wherein a reflection spectrum of each of the plurality of sensor fiber optic gratings is convolved with a corresponding one of the at least one optical filter. 
     
     
         20 . The interrogator of  claim 1  wherein an output intensity of each at least one filter varies approximately linearly with a reflection spectrum center wavelength of a corresponding one of the plurality of sensor fiber optic gratings.