Multi-channel wavelength slicing using an etalon-based interleaver for dense wavelength division multiplexing

Abstract

A versatile, wavelength-slicing device, referred to herein as an optical spectrum synthesizer (OSS), provides new avenues and technologies for optical communication applications. Specifically, OSS separates a composed optical signal into two output spectra. Each output spectrum carries a multiple of optical communication signal channels. The bandwidth of each channel and spacing between adjacent channels may differ from one output to the other. The cascades of OSS devices, the combinations of OSS with prior art components and modules, and other new devices to be used in conjunction with OSS lead to new Spectrum Devices that add new dimensions to existing and new optical network architectures. The invention of OSS leads to new Spectrum Wavelength Division Multiplexing and management devices based on cascades of OSS devices. Examples of these devices include Spectrum Multiplexer, Spectrum Demultiplexer and Spectrum Add Drop Module. The combinations of OSS and other prior art devices also lead to several new Spectrum devices and modules. Examples of these include, Spectrum Switch, Spectrum Cross-Connect and Spectrum Long Haul Transport Modules. Other devices designed to be used in conjunction with OSS, e.g., 1/n Multiplexer and 1/n Demultiplexer, can also be used to form new devices and modules.

What is claimed is:  
     
         1 . An apparatus for receiving a composite optical signal defined by a plurality of distinct channels having spaced center wavelengths in a continuous frequency spectrum; the apparatus generating two separate output optical signals from the received signal; the apparatus comprising: 
 a wavelength-dependent optical device for segregating said received signal into said two separate output optical signals having non-continuous spectra; one of said output signals having a greater number of said distinct channels than the other of said output signals.    
     
     
         2 . The apparatus recited in  claim 1  wherein the non-continuous spectrum of one of said output signals is the complement of the non-continuous spectrum of the other of said output signals.  
     
     
         3 . The apparatus recited in  claim 1  wherein the combined non-continuous spectra of said two output signals contain all of said distinct channels of said continuous frequency spectrum of said received optical signal.  
     
     
         4 . The apparatus recited in  claim 1  wherein each of said non-continuous spectra of said output optical signals comprises a plurality of passbands that are spaced from one another in frequency; the number of said distinct channels in each of said passbands of one of said output signals being greater than the number of said distinct channels in each of said passbands of the other of said output signals.  
     
     
         5 . The apparatus recited in  claim 1  wherein said wavelength-dependent optical device comprises: 
 a plurality of adjacent optical cavities each having at least one partially reflective surface.  
 
     
     
         6 . The apparatus recited in  claim 1  wherein said wavelength-dependent optical device comprises: 
 at least two adjacent optical cavities having a total of at least three partially reflective surfaces; said optical cavities having a selected thickness for achieving said separate output optical signals.  
 
     
     
         7 . The apparatus recited in  claim 6  wherein at least one of said optical cavities comprises an air spaced optical cavity.  
     
     
         8 . The apparatus recited in  claim 1  wherein said wavelength-dependent optical device comprises: 
 at least three adjacent optical cavities having a total of at least four partially reflective surfaces; said optical cavities having a selected thickness for achieving said separate output optical signals.  
 
     
     
         9 . The apparatus recited in  claim 8  wherein at least one of said optical cavities comprises an air spaced optical cavity.  
     
     
         10 . The apparatus recited in  claim 6  wherein each of said partially reflective surfaces has a reflection coefficient in the range of 5% to 90%.  
     
     
         11 . The apparatus recited in  claim 8  wherein each of said partially reflective surfaces has a reflection coefficient in the range of 5% to 90%.  
     
     
         12 . The apparatus recited in  claim 1  wherein said received composite signal is incident on said wavelength-dependent optical device at an angle of less than 10 degrees from normal.  
     
     
         13 . The apparatus recited in  claim 1  wherein said wavelength-dependent optical device comprises materials having selected thermal expansion coefficients to reduce the temperature sensitivity of said device.  
     
     
         14 . The apparatus recited in  claim 1  wherein said wavelength-dependent optical device is positioned in proximity to temperature control apparatus for selecting temperature adjacent said device.  
     
     
         15 . An apparatus for receiving a composite optical signal defined by a plurality of distinct channels having center wavelengths in a continuous frequency spectrum; the apparatus comprising: 
 a wavelength-dependent optical device for segregating said received signal into N separate output optical signals having non-continuous spectra, where N≧3; each of said output optical signals having a substantially equal number of said distinct channels.    
     
     
         16 . A spectrum add and drop apparatus for receiving a first composite optical signal defined by a plurality of distinct channels having spaced center wavelengths in a continuous frequency spectrum and generating a second composite optical signal wherein at least some of said distinct channels from said first composite signal are replaced by substitute distinct channels in said second composite signal; the apparatus comprising: 
 a first wavelength-dependent optical device for segregating said first composite signal into two separate output optical signals having non-continuous spectra; one of said output signals having a greater number of said distinct channels than the other of said output signals;    a second wavelength-dependent optical device connected to said first wavelength-dependent optical device for receiving said output signal having a greater number of said distinct channels, but receiving a substitute for the other output signal of said first wavelength-dependent optical device; said second wavelength-dependent optical device generating said second composite optical signal.    
     
     
         17 . The apparatus recited in  claim 1  further comprising at least one wavelength periodic filter connected for filtering of at least one of said output signals.  
     
     
         18 . A method for demultiplexing a composite optical signal with different center-wavelengths represented by λ 1 , λ 2 , λ 3 , . . . λ n  where n is a positive integer and said wavelengths are equally spaced, comprising steps of 
 a) receiving said composite optical signal into an asymmetric wavelength slicing device through a device input port; and  
 b) slicing said composite signal and extracting a first composite optical signal comprising a first set of channels λ 1 , λ a , λ b , λ c , . . . λ n−a+2  through a first output port, and a second composite optical signal comprising a second set of channels λ 2 , λ d , λ e , λ f , . . . λ n  through a second output port wherein said second set of data channels is complimentary to said first set of data channels and a spacing (λ 1 −λ a ) between λ 1  and λ a  is different from a spacing (λ 2 −λ d ) between λ 2  and λ d .  
 
     
     
         19 . A method for demultiplexing a composite optical signal with different center-wavelengths represented by λ 1 , λ 2 , λ 3 , λ 4 , . . . λ n  where n is a positive integer and the wavelengths are equally spaced, comprising steps of 
 a) receiving said composite optical signal into an asymmetric wavelength slicing device through a device input port; and  
 b) slicing said composite signal and extracting a first composite optical signal comprising a first set of channels λ 1 , λ 3 , λ 5 , λ 7 , λ n−1  through a first output port, and a second composite optical signal comprising a second set of channels λ 2 , λ 4 , λ 6 , λ 8 , . . . λ n  through a second output port wherein said second set of data channels is complimentary to said first set of data channels but having a different bandwidth.  
 
     
     
         20 . A asymmetric wavelength slicing device for demultiplexing a composite optical signal with different center-wavelengths represented by λ 1 , λ 2 , λ 3 , λ 4 , . . . λ n  where n is a positive integer and the wavelengths are equally spaced, comprising at least an input port and two output ports, 
 said composite signal being sliced into a first composite optical signal comprising a first set of channels λ 1 , λ a , λ b , λ c , . . . λ n−a+2  through a first output port, and a second composite optical signal comprising a second set of channels λ 2 , λ d , λ e , λ f , . . . λ n  through a second output port wherein said second set of data channels is complimentary to said first set of data channels, but the spacing between λ 1  and λ a  is different from the spacing between λ 2  and λ d .  
 
     
     
         21 . A asymmetric wavelength slicing device for demultiplexing a composite optical signal with different center-wavelengths represented by λ 1 , λ 2 , λ 3 , λ 4 , . . . λ n  where n is a positive integer and the wavelengths are equally spaced, comprising: 
 at least an input port and two output ports, said composite signal being sliced into a first composite optical signal comprising a first set of channels λ 1 , λ 3 , λ 5 , λ 7 , . . . λ n−1  through a first output port, and a second composite optical signal comprising a second set of channels λ 2 , λ 4 , λ 6 , λ 8 , . . . λ n  through a second output port wherein said second set of data channels is complimentary to said first set of data channels, but the bandwidth is different from the bandwidth of said first set of data channels.  
 
     
     
         22 . The method recited in  claim 18  wherein step b) is carried out by placing an etalon-based wavelength slicing device in the path of said received composite optical signal, said device having at least two optical cavities having a total of at least three partially reflective surfaces, said optical cavities having a selected thickness for achieving said first and second composite optical signals.  
     
     
         23 . The method recited in  claim 19  wherein step b) is carried out by placing an etalon-based wavelength slicing device in the path of said received composite optical signal, said device having at least two optical cavities having a total of at least three partially reflective surfaces, said optical cavities having a selected thickness for achieving said first and second composite optical signals.  
     
     
         24 . The device recited in  claim 20  further comprising an etalon-based wavelength slicing device in the path of said received composite optical signal, said device having at least two optical cavities having a total of at least three partially reflective surfaces, said optical cavities having a selected thickness for achieving said first and second composite optical signals.  
     
     
         25 . The device recited in  claim 21  further comprising an etalon-based wavelength slicing device in the path of said received composite optical signal, said device having at least two optical cavities having a total of at least three partially reflective surfaces, said optical cavities having a selected thickness for achieving said first and second composite optical signals.  
     
     
         26 . A spectral demultiplexer for use in optical communications systems: the demultiplexer receiving a composite optical signal having spectral components in any of a plurality of wavelength channels in a continuous spectrum and generating a plurality of N output optical signals each having spectral components in 1/N of said wavelength channels in respective non-continuous spectra.  
     
     
         27 . The spectral demultiplexer recited in  claim 26  where N≧3.  
     
     
         28 . A spectral multiplexer for use in optical communications systems; the multiplexer receiving a plurality of N input optical signals each having different discontinuous spectral components in 1/N wavelength channels of a plurality of wavelength channels in a continuous spectrum, and generating an output composite optical signal having the spectral components of all of said N input optical signals.  
     
     
         29 . The spectral multiplexer recited in  claim 28  wherein N≧3.  
     
     
         30 . A group of optical signal demultiplexers comprising a plurality of demultiplexers each receiving a different composite optical signal having a plurality of spaced center channel wavelengths in a non-continuous spectrum and each such demultiplexer producing a plurality of individual output optical signals each having a unique one of said spaced center channel wavelengths.  
     
     
         31 . A group of optical signal multiplexers comprising a plurality of multiplexers each receiving a plurality of individual input signals each such signal having a center channel wavelength which is spaced from the center channel wavelength of the other such signals; each such multiplexer producing a different composite output signal, each such different output signal comprising all of the center channel wavelengths of the individual input signals of the multiplexer from which the output signal is produced.  
     
     
         32 . The apparatus recited in  claim 15  further comprising an N×N switch for placing said output optical signals on N output lines in any selected order.