Dispersion-compensated optical wavelength router and cascaded architectures

Abstract

An optical wavelength router includes a beamsplitter, a first resonator, and a second resonator. The beamsplitter separates an input signal into a first beam and a second beam. The first resonator reflects the first beam and has a partially reflective front surface and a highly reflective back surface spaced a first optical thickness from the front surface. The second resonator reflects the second beam and has a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface. The difference between the optical thicknesses of the first and second resonators is approximately equal to one-eighth wavelength.

1 . An optical wavelength router comprising: 
 a beamsplitter operable to separate an input signal into a first beam and a second beam;    a first resonator operable to reflect the first beam and having a partially reflective front surface and a highly reflective back surface spaced a first optical thickness from the front surface; and    a second resonator operable to reflect the second beam and having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-eighth wavelength.    
   
   
       2 . The router of  claim 1 , wherein the beamsplitter is further operable to process the first beam and the second beam to generate a first output signal for communication to a first output port and to generate a second output signal for communication to a second output port, the first output signal comprising a first subset of channels from the input signal and the second output signal comprising a second subset of channels from the input signal.  
   
   
       3 . The router of  claim 2 , wherein: 
 the input signal comprises an input spectral band;    the first output signal comprises a first subset of the input spectral band; and    the second output signal comprises a second subset of the input spectral band that is complementary to the first subset of the input spectral band.    
   
   
       4 . The router of  claim 1 , wherein: 
 the input signal comprises a first input signal;    the beamsplitter is operable to separate a second input signal into a third beam and a fourth beam;    the first resonator is further operable to reflect the third beam;    the second resonator is further operable to reflect the fourth beam;    the beamsplitter is further operable to process the first beam, the second beam, the third beam, and the fourth beam to generate an output signal for communication to an output port; and    the output signal comprises channels of the first input signal combined with channels of the second input signal.    
   
   
       5 . The router of  claim 1 , wherein: 
 the first resonator has a first center wavelength; and    the second resonator has a second center wavelength; and    the second center wavelength is offset relative to the first center wavelength by approximately one quarter of the free spectral range of the first resonator.    
   
   
       6 . The router of  claim 1 , wherein: 
 the first beam propagates along an optical path having a first optical path length;    the second beam propagates along an optical path having a second optical path length; and    the difference between the first optical path length and the second optical path length is approximately equal to one half of the first optical thickness.    
   
   
       7 . An optical device, comprising: 
 a first stage optical wavelength router that receives an input wavelength division multiplexed signal and that generates a first output signal comprising a first subset of wavelength channels from the input signal and a second output signal comprising a second subset of wavelength channels from the input signal, wherein the first stage optical wavelength router is characterized by a chromatic dispersion profile having a first frequency offset; and    a second stage optical wavelength router that receives the first output signal and that generates a third output signal and a fourth output signal, wherein the second stage optical wavelength router is characterized by the chromatic dispersion profile having a second frequency offset such that the difference between the first frequency offset and the second frequency offset comprises one-half of the period of the chromatic dispersion profile.    
   
   
       8 . The optical device of  claim 7 , wherein the first stage optical wavelength router comprises: 
 a beamsplitter that separates the input signal into a first beam and a second beam;    a first resonator that reflects the first beam and having a partially reflective front surface and a highly reflective back surface spaced a first optical thickness from the front surface; and    a second resonator that reflects the second beam and having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-quarter wavelength.    
   
   
       9 . The optical device of  claim 7 , wherein the second stage optical wavelength router comprises: 
 a beamsplitter that separates the first output signal into a first beam and a second beam;    a first resonator that reflects the first beam and having a partially reflective front surface and a highly reflective back surface spaced a first optical thickness from the front surface; and    a second resonator that reflects the second beam and having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-quarter wavelength.    
   
   
       10 . The optical device of  claim 8 , wherein the first resonator and the second resonator each have approximately the same front mirror reflectivity.  
   
   
       11 . The optical device of  claim 7 , wherein: 
 the chromatic dispersion profile of the first stage optical wavelength router is offset in a first direction by a particular frequency; and    the chromatic dispersion profile of the second stage optical wavelength router is offset by the particular frequency in a second direction substantially opposite to that of the first direction.    
   
   
       12 . The optical device of  claim 7 , wherein: 
 the magnitude of the first frequency offset is substantially zero; and    the magnitude of the second frequency offset is substantially one-half of the period of the chromatic dispersion profile.    
   
   
       13 . The optical device of  claim 7 , wherein the chromatic dispersion profile of the second stage optical wavelength router is substantially opposite to the chromatic dispersion profile of the first stage optical wavelength router.  
   
   
       14 . An optical device, comprising: 
 a first stage optical wavelength router that receives a first input signal comprising a first subset of wavelength channels and a second input signal comprising a second subset of wavelength channels, and that generates a first output signal comprising the first and second subsets of wavelength channels, wherein the first stage optical wavelength router is characterized by a chromatic dispersion profile having a first frequency offset; and    a second stage optical wavelength router that receives the first output signal and a third input signal comprising a third subset of wavelength channels, and that generates a second output signal comprising the first, second, and third subsets of wavelength channels, wherein the second stage optical wavelength router is characterized by the chromatic dispersion profile having a second frequency offset such that the difference between the first frequency offset and the second frequency offset comprises one-half of the period of the chromatic dispersion profile.    
   
   
       15 . The optical device of  claim 14 , wherein the first stage optical wavelength router comprises: 
 a beamsplitter;    a first resonator having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface; and    a second resonator having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-quarter wavelength.    
   
   
       16 . The optical device of  claim 14 , wherein the second stage optical wavelength router comprises: 
 a beamsplitter;    a first resonator having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface; and    a second resonator having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-quarter wavelength.    
   
   
       17 . The optical device of  claim 14 , wherein: 
 the chromatic dispersion profile of the first stage optical wavelength router is offset in a first direction by a particular frequency; and    the chromatic dispersion profile of the second stage optical wavelength router is offset by the particular frequency in a second direction substantially opposite to that of the first direction.    
   
   
       18 . The optical device of  claim 14 , wherein: 
 the magnitude of the first frequency offset is substantially zero; and    the magnitude of the second frequency offset is substantially one-half of the period of the chromatic dispersion profile.    
   
   
       19 . The optical device of  claim 14 , wherein the chromatic dispersion profile of the second stage optical wavelength router is substantially opposite to the chromatic dispersion profile of the first stage optical wavelength router.  
   
   
       20 . An optical device, comprising: 
 a first stage optical wavelength router operable to receive an input wavelength division multiplexed signal and to generate a first output signal comprising a first subset of wavelength channels from the input signal and a second output signal comprising a second subset of wavelength channels from the input signal, wherein the first stage optical wavelength router is characterized by a chromatic dispersion profile having a first slope at a center frequency of a particular wavelength channel; and    a second stage optical wavelength router operable to receive the first output signal and to generate a third output signal and a fourth output signal, wherein the second stage optical wavelength router is characterized by a chromatic dispersion profile having a second slope at the center frequency that is substantially opposite to the first slope.    
   
   
       21 . The optical device of  claim 20 , wherein the chromatic dispersion profile of the second stage optical wavelength router is substantially opposite to the chromatic dispersion profile of the first stage optical wavelength router over a range of frequencies surrounding the center frequency.  
   
   
       22 . The optical device of  claim 20 , wherein the first stage optical wavelength router comprises: 
 a beamsplitter operable to separate an input signal into a first beam and a second beam;    a mirror operable to reflect the first beam; and    a resonator operable to reflect the second beam and having a partially reflective front surface and a highly reflective back surface.    
   
   
       23 . The optical device of  claim 20 , wherein the second stage optical wavelength router comprises: 
 a beamsplitter operable to separate an input signal into a first beam and a second beam;    a first resonator operable to reflect the first beam and having a partially reflective front surface and a highly reflective back surface spaced a first optical thickness from the front surface; and    a second resonator operable to reflect the second beam and having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-quarter wavelength.    
   
   
       24 . An optical device, comprising: 
 a first stage optical wavelength router operable to receive a first input signal comprising a first subset of wavelength channels and a second input signal comprising a second subset of wavelength channels, and further operable to generate a first output signal comprising the first and second subsets of wavelength channels, wherein the first stage optical wavelength router is characterized by a chromatic dispersion profile having a first slope at a center frequency of a particular wavelength channel; and    a second stage optical wavelength router operable to receive the first output signal and a third input signal comprising a third subset of wavelength channels, and further operable to generate a second output signal comprising the first, second, and third subsets of wavelength channels, wherein the second stage optical wavelength router is characterized by a chromatic dispersion profile having a second slope at the center frequency that is substantially opposite to the first slope.    
   
   
       25 . The optical device of  claim 24 , wherein the chromatic dispersion profile of the second stage optical wavelength router is substantially opposite to the chromatic dispersion profile of the first stage optical wavelength router over a range of frequencies surrounding the center frequency.  
   
   
       26 . The optical device of  claim 24 , wherein the first stage optical wavelength router comprises: 
 a beamsplitter;    a first resonator having a partially reflective front surface and a highly reflective back surface spaced a first optical thickness from the front surface; and    a second resonator having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-quarter wavelength.    
   
   
       27 . The optical device of  claim 24 , wherein the second stage optical wavelength router comprises: 
 a beamsplitter operable to separate an input signal into a first beam and a second beam;    a mirror operable to reflect the first beam; and    a resonator operable to reflect the second beam and having a partially reflective front surface and a highly reflective back surface.    
   
   
       28 . An optical device, comprising: 
 a first stage optical wavelength router operable to receive an input wavelength division multiplexed signal and to generate a first output signal comprising a first subset of wavelength channels from the input signal and a second output signal comprising a second subset of wavelength channels from the input signal, wherein the first stage optical wavelength router is characterized by a chromatic dispersion profile having a first slope over a first range of frequencies and a second slope over a second range of frequencies, the second slope being substantially opposite to the first slope; and    a second stage optical wavelength router operable to receive the first output signal and to generate a third output signal and a fourth output signal, wherein the second stage optical wavelength router is characterized by a chromatic dispersion profile having the second slope over the first range of frequencies and the first slope over the second range of frequencies.    
   
   
       29 . The optical device of  claim 28 , wherein the chromatic dispersion profile associated with the second stage optical wavelength router is substantially opposite to the chromatic dispersion profile associated with the first stage optical wavelength router over the first and second range of frequencies.  
   
   
       30 . The router of  claim 28 , wherein the first stage optical wavelength router comprises: 
 a beamsplitter operable to separate an input signal into a first beam and a second beam;    a first resonator operable to reflect the first beam and having a partially reflective front surface and a highly reflective back surface spaced a first optical thickness from the front surface; and    a second resonator operable to reflect the second beam and having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-eighth wavelength.    
   
   
       31 . The router of  claim 28 , wherein the second stage optical wavelength router comprises: 
 a beamsplitter operable to separate an input signal into a first beam and a second beam;    a first resonator operable to reflect the first beam and having a partially reflective front surface and a highly reflective back surface spaced a first optical thickness from the front surface; and    a second resonator operable to reflect the second beam and having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-eighth wavelength.    
   
   
       32 . An optical device, comprising: 
 a first stage optical wavelength router operable to receive a first input signal comprising a first subset of wavelength channels and a second input signal comprising a second subset of wavelength channels, and further operable to generate a first output signal comprising the first and second subsets of wavelength channels, wherein the first stage optical wavelength router is characterized by a chromatic dispersion profile having a first slope over a first range of frequencies and a second slope over a second range of frequencies, the second slope being substantially opposite to the first slope; and    a second stage optical wavelength router operable to receive the first output signal and a third input signal comprising a third subset of wavelength channels, and further operable to generate a second output signal comprising the first, second, and third subsets of wavelength channels, wherein the second stage optical wavelength router is characterized by a chromatic dispersion profile having the second slope over the first range of frequencies and the first slope over the second range of frequencies.    
   
   
       33 . The optical device of  claim 32 , wherein the chromatic dispersion profile associated with the second stage optical wavelength router is substantially opposite to the chromatic dispersion profile associated with the first stage optical wavelength router over the first and second range of frequencies.  
   
   
       34 . The router of  claim 32 , wherein the first stage optical wavelength router comprises: 
 a beamsplitter;    a first resonator having a partially reflective front surface and a highly reflective back surface spaced a first optical thickness from the front surface; and    a second resonator having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-eighth wavelength.    
   
   
       35 . The router of  claim 32 , wherein the second stage optical wavelength router comprises: 
 a beamsplitter;    a first resonator having a partially reflective front surface and a highly reflective back surface spaced a first optical thickness from the front surface; and    a second resonator having a partially reflective front surface and a highly reflective back surface spaced a second optical thickness from the front surface;    wherein the difference between the first optical thickness and the second optical thickness is approximately equal to one-eighth wavelength.