Method, apparatus and system for minimally intrusive fiber identification

Abstract

A method, apparatus and system for minimally intrusive fiber identification includes imparting a time-varying modulation onto an optical signal propagating in an optical fiber and subsequently detecting the presence of the time-varying modulation in the optical signal transmitting through the fiber to identify the fiber. In a specific embodiment of the invention, a time-varying curvature is imposed on the fiber to be identified and the presence of the resultant time variation in the transmitted power of a propagating optical signal is subsequently detected for identification of the manipulated fiber.

1 . A method for identifying an optical fiber, comprising: 
 imparting a time-varying modulation onto an optical signal propagating in said optical fiber; and    detecting the presence of said imparted time-varying modulation to identify said optical fiber;    wherein said imparting and detecting do not interrupt the propagation of said optical signal along said optical fiber.    
   
   
       2 . The method of  claim 1 , wherein said time-varying modulation is imparted on said optical signal by varying a property of said optical fiber as a function of time.  
   
   
       3 . The method of  claim 2 , wherein a curvature of at least a portion of said optical fiber is varied as a function of time such that a time-varying loss of power is generated in said propagating optical signal.  
   
   
       4 . The method of  claim 3 , wherein the curvature of said optical fiber is varied by vibrating at least a portion of said optical fiber.  
   
   
       5 . The method of  claim 4 , wherein an amplitude of said vibration is small compared to the average power of said propagating optical signal such that said propagating optical signal is minimally affected.  
   
   
       6  The method of  claim 2 , wherein a birefringence of at least a portion of said optical fiber is varied as a function of time such that a polarization of said propagating optical signal is varied as a function of time.  
   
   
       7 . The method of  claim 6  wherein the birefringence of said optical fiber is varied via a time-varying magnetic field.  
   
   
       8 . The method of  claim 6 , wherein the birefringence of said optical fiber is varied via a time-varying electric field.  
   
   
       9 . The method of  claim 1 , wherein said time-varying modulation is imparted on said optical signal by varying a frequency of said propagating optical signal is varied as a function of time.  
   
   
       10 . The method of  claim 9 , wherein the frequency of said propagating optical signal is varied as a function of time through time-varying non-linear interactions.  
   
   
       11 . The method of  claim 10 , wherein said time-varying non-linear interactions are created through the interaction of acoustic waves with said propagating optical signal in said optical fiber.  
   
   
       12 . The method of  claim 1 , wherein said time-varying modulation is imparted on said optical signal by a source of said optical signal.  
   
   
       13 . The method of  claim 12 , wherein said time-varying modulation is imparted on said optical signal at an intermediate point between optical fibers in a fiber path.  
   
   
       14 . The method of  claim 1 , further comprising bending said optical fiber such that light is scattered out of said fiber to enable said detecting.  
   
   
       15 . An apparatus for identifying an optical fiber, comprising: 
 at least one modulating device for imparting a time-varying modulation onto an optical signal propagating in said optical fiber;    at least one fiber bending device for bending said optical fiber such that at least a portion of the optical signal is scattered out of said optical fiber; and    at least one detector, said detector receiving the scattered portion of the optical signal for detecting the presence of said imparted time-varying modulation to identify said optical fiber.    
   
   
       16 . The apparatus of  claim 15 , wherein said imparting and detecting do not interrupt the propagation of said optical signal along said optical fiber.  
   
   
       17 . The apparatus of  claim 15 , wherein said optical fiber comprises a plurality of interconnected optical fibers.  
   
   
       18 . The apparatus of  claim 15 , further comprising a control unit, said control unit comprising a memory for storing information and program instructions and a processor for executing said instructions to configure the apparatus to perform the steps of: 
 imparting a time-varying modulation onto the optical signal propagating in said optical fiber; and    detecting the presence of said imparted time-varying modulation to identify said optical fiber.    
   
   
       19 . The apparatus of  claim 18 , wherein said control unit is further adapted to cause a source of said optical signal to impart a time-varying modulation onto said optical signal.  
   
   
       20 . The apparatus of  claim 15 , wherein said at least one modulating device comprises a transmitter head and said bending device and said detector comprise a receiver head.  
   
   
       21 . The apparatus of  claim 20 , wherein said transmitter head further comprises a bending device and a detector and said receiver head further comprises a modulating device.  
   
   
       22 . The apparatus of  claim 15 , wherein said modulating device comprises a vibrating piston and said vibrating piston varies the curvature of at least a portion of said optical fiber as a function of time such that a time-varying loss of power is generated in said propagating optical signal.  
   
   
       23 . The apparatus of  claim 15 , wherein said modulating device comprises a piezo-electric transducer and said piezo-electric transducer varies the curvature of at least a portion of said optical fiber as a function of time such that a time-varying loss of power is generated in said propagating optical signal.  
   
   
       24 . The apparatus of  claim 15 , wherein said fiber bending device is adjustable for varying the radius of the bend on said optical fiber.  
   
   
       25 . The apparatus of  claim 15 , wherein said fiber bending device comprises at least one anvil.  
   
   
       26 . The apparatus of  claim 15 , further comprising at least one lightguide for guiding the scattered portion of the optical signal to said at least one detector.  
   
   
       27 . The apparatus of  claim 26 , wherein said lightguide comprises a plexiglass lightguide.  
   
   
       28 . The apparatus of  claim 15 , wherein said modulating device comprises a means for introducing a varying magnetic field and said means for introducing a varying magnetic field varies the polarization of said propagating optical signal as a function of time by varying the birefringence of said optical fiber as a function of time.  
   
   
       29 . The apparatus of  claim 15 , wherein said means for introducing a varying magnetic field comprises a solenoid.  
   
   
       30 . The apparatus of  claim 28 , wherein said detector further comprises a polarizer.  
   
   
       31 . The apparatus of  claim 15 , wherein said modulating device comprises a means for varying the frequency of said propagating optical signal as a function of time through non-linear interactions.  
   
   
       32 . The apparatus of  claim 31 , wherein said means for varying the frequency of said propagating optical signal as a function of time comprises a means for introducing acoustic waves and said means for introducing acoustic waves varies the frequency of said propagating optical signal as a function of time through non-linear interactions of said acoustic waves and said propagating optical signal.  
   
   
       33 . The apparatus of  claim 31 , wherein said means for varying the frequency of said propagating optical signal as a function of time comprises an acoustic horn.  
   
   
       34 . The apparatus of  claim 15 , further comprising at least a second detector for detecting said time-varying modulation near the point of modulation such that a subsequent downstream detection of said modulation may be compared to the modulation detected near the point of modulation for the identification of said optical fiber.  
   
   
       35 . The apparatus of  claim 15 , wherein said apparatus is implemented to verify communications between at least two points in a passive optical network.  
   
   
       36 . An apparatus for identifying an optical fiber, comprising: 
 a means for imparting a time-varying modulation onto an optical signal propagating in said optical fiber;    a means for bending said optical fiber such that at least a portion of the optical signal is scattered out of said optical fiber; and    a means for detecting the presence of said imparted time-varying modulation to identify said optical fiber.    
   
   
       37 . The apparatus of  claim 36 , further comprising: 
 a means for guiding the scattered portion of said optical signal to said means for detecting.    
   
   
       38 . A system for identifying at least some of a plurality of optical fibers, comprising: 
 a plurality of fiber bending devices, each of said devices connected to a respective one of said optical fibers for bending said respective optical fiber such that at least a portion of a respective optical signal is scattered out of a respective optical fiber; and    at least one detector, said detector receiving the scattered portion of a respective optical signal from a respective optical fiber for detecting the presence of a respective imparted time-varying modulation to identify said optical fibers.    
   
   
       39 . The system of  claim 38 , wherein said respective time-varying modulation is imparted on each of said respective optical signals by a respective transmitter.  
   
   
       40 . The system of  claim 38 , further comprising a plurality of modulating devices, each of said devices acting on a respective one of said optical fibers for imparting said time-varying modulation onto a respective optical signal propagating in a respective optical fiber.  
   
   
       41 . The system of  claim 38 , further comprising control unit, said control unit comprising a memory for storing information and program instructions and a processor for executing said instructions to control the components of said system to configure the system to perform the steps of: 
 imparting a time-varying modulation onto a respective optical signal propagating in a respective optical fiber; and    detecting the presence of a respective imparted time-varying modulation to identify said optical fibers.    
   
   
       42 . The system of  claim 41 , wherein said control unit generates a control signal for causing a respective transmitter to impart a time-varying modulation on respective optical signals to be propagated via said plurality of optical fibers.  
   
   
       43 . The system of  claim 38 , wherein said system comprises a plurality of detectors, each of said detectors receiving the scattered portion of a respective optical signal from a respective optical fiber.