Array and method for monitoring the performance of DWDM multiwavelength systems

Abstract

A system and method for monitoring all the characteristic parameters of a DWDM communication system is implemented with two variants. Firstly, this is achieved by means of a specific grating spectrometer displaying a high 5 resolution and a high-speed sampling of the measured values, and secondly by the application of an opto-electronic cross correlator as a purely electronic solution. The grating spectrometer is expediently a particular system in a mixed array according to Ebert and Fastie, wherein the light to be measured passes four times through the grating in a specific manner. The opto-10 electronic cross correlator can mix the working light with a reference light tunable in terms of its frequency to form an electrical low-frequency signal that is analyzed in a high-impedance operation.

1 - 19 . (canceled)  
   
   
       20 . A system for monitoring the performance of a DWDM multi-wavelength system comprising: 
 means for converting a portion of an optical signal from the DWDM multi-wavelength system at a particular wavelength to an electrical signal;    wherein the converting means comprises    an optical unit having the optical signal as an input and the particular wavelength portion of the optical signal as an output; and    means for processing the electrical signal to determine the performance of the DWDM multi-wavelength system at the particular wavelength and for controlling the converting means so that each particular wavelength of the DWDM multi-wavelength system is processed.    
   
   
       21 . The system as recited in  claim 20  wherein the converting means comprises a narrow-band tunable bandpass filter having the optical signal as an input and providing the electrical signal the particular wavelength portion of the optical signal as an output.  
   
   
       22 . The system as recited in  claim 20  wherein the converting means comprises: 
 an optical unit having the optical signal as an input and the particular wavelength portion as an output; and    a photodetector having the particular wavelength portion as an input and the electrical signal as an output.    
   
   
       23 . The system as recited in  claim 22  wherein the converting means further comprises a lowpass filter having an input coupled to the output of the photodetector and having an output to produce the electrical signal.  
   
   
       24 . The system as recited in  claim 22  wherein the optical unit comprises a grating spectrometer having the optical signal as an input and providing the particular wavelength portion as an output.  
   
   
       25 . The system as recited in  claim 24  wherein the grating spectrometer comprises: 
 a movable grating having a wavelength range that covers a measurement range for the DWDM multi-wavelength system;    an imaging element for reflecting the optical signal; and    a beam deflection system mounted such that the optical signal incident on the imaging element and the optical signal exiting from the imaging element are essentially symmetrical, the movement of the movable grating selecting the particular wavelength portion, and the optical signal being subjected to multiple passes between the movable grating and the image element.    
   
   
       26 . The system as recited in  claim 25  wherein the movable grating is mounted with respect to the imaging element and the beam deflection system in a combined array according to Ebert and Fastie and by approximation in a Littrow array.  
   
   
       27 . The system as recited in  claim 25  wherein the movable grating comprises one selected from the group consisting of a ruled grating and a blazed grating.  
   
   
       28 . The system as recited in  claim 25  further comprising means for determining an angular position of the movable grating, the angular position determining the particular wavelength portion.  
   
   
       29 . The system as recited in  claim 28  wherein the determining means comprises: 
 a high precision light source for generating a focused beam;    a reflecting surface rigidly coupled to the movable grating upon which the focused beam impinges; and    a position sensor for receiving the focused beam reflected from the reflecting surface to determine the angular position.    
   
   
       30 . The system as recited in  claim 25  further comprising means for moving the angular position of the grating to select the particular wavelength portion.  
   
   
       31 . The system as recited in  claim 29  wherein the position sensor comprises: 
 an incremental scale that influences the intensity of the reflected focused beam as a function of the point on the incremental scale upon which the reflected focused beam impinges; and    a detector for detecting an intensity of light from the incremental scale, the intensity being a measure of the angular position.    
   
   
       32 . The system as recited in  claim 20  wherein the converting means comprises: 
 means for mixing the optical signal with a tunable reference optical signal to produce a combined optical signal; and    a photodetector for converting the combined optical signal to the electrical signal.