Wavelength tunable filter device for fiber optic systems

Abstract

A wavelength tunable filter for optical communication systems has an optical fiber containing a Bragg grating disposed within a compliant support block. A length of the fiber is wrapped in a spiral of fixed pitch around the longitudinal axis of a cylindrical polymer support block. The support block is placed within a support frame to which a micrometer screw assembly is attached and oriented to apply a variable mechanical load substantially parallel to the longitudinal axis of the cylindrical support block. Application of the load introduces a strain on the support block, changing the period of the refractive index in the fiber Bragg grating with a resulting shift in the Bragg reflection peak.

1 - 12 . Cancelled.  
     
     
         13 . A method of filtering an optical signal, comprising: 
 coupling an optical signal into an optical fiber;    receiving a filtered optical signal out of said optical fiber; and    varying a load applied to a compliant support block having at least a portion of said optical fiber embedded therein,    wherein said portion of said optical fiber embedded in said compliant support block has a periodic variation in refractive index along at least a portion thereof to form a fiber Bragg grating in said optical fiber.    
     
     
         14 . A method of filtering an optical signal according to  claim 13 , 
 wherein said varying said load applied to said compliant support block changes a transmission characteristic of said fiber Bragg grating.    
     
     
         15 . A method of filtering an optical signal according to  claim 13 , 
 wherein said compliant support block has a substantially cylindrical shape, and    wherein said varying said load applied to said compliant support block comprises changing a compressional force applied between opposing ends of said compliant support block.    
     
     
         16 . A method of filtering an optical signal according to  claim 13 , wherein said filtered optical signal is reflected from said fiber Bragg grating.  
     
     
         17 . A method of filtering an optical signal according to  claim 13 , wherein said filtered optical signal is transmitted through said fiber Bragg grating.  
     
     
         18 . Canceled  
     
     
         19 . A method of making a tunable optical filter, comprising: 
 disposing an optical fiber having at least a fiber Bragg grating portion into a substantially cylindrical mold;    pouring support material into a substantially cylindrical mold, said support material being compliant when it sets; and    allowing said support material to set.    
     
     
         20 . A method of making a tunable optical filter according to  claim 19 , further comprising attaching a load-supplying assembly to said support material.  
     
     
         21 . A method of making a tunable optical filter according to  claim 19 , further comprising attaching said optical fiber having said fiber Bragg grating portion to a core of pre-set support material prior to said pouring support material into said substantially cylindrical mold.  
     
     
         22 . A method of filtering an optical signal according to  claim 13 , wherein said optical signal coupled into said optical fiber is a wavelength division multiplexed optical signal having a plurality of signal channels.  
     
     
         23 . A method of filtering an optical signal according to  claim 22 , wherein said filtered optical signal is a single channel selected from said plurality of signal channels.