Apparatus for broadband wavelength conversion of dual-polarization phase-encoded signal

Abstract

An apparatus and method for wavelength conversion of a signal, for example, a dual-polarization signal, is disclosed. The apparatus implements a single-loop counter-propagating wavelength conversion scheme which provides both up-conversion and down-conversion of the signal within the same loop. Nonlinear wavelength conversion devices in the loop provide both up-conversion and down-conversion of the polarization components of the signal within the loop depending on whether the polarization component travels through the nonlinear conversion device in a clockwise or a counter-clockwise direction. The wavelength-converted signal is available to be extracted from the wavelength-conversion loop. An all-optical wavelength-division multiplexing transponder based on the wavelength-conversion scheme is also disclosed.

What is claimed is: 
     
         1 . A wavelength converter, comprising:
 an input for receiving a signal having a first wavelength; and   a wavelength-conversion loop capable of converting the first wavelength of the signal to a second wavelength, the first wavelength and the second wavelength separated from each other by a broad spectral range;   wherein the wavelength-conversion loop is capable of up-converting the first wavelength to the second wavelength without using broadband components.   
     
     
         2 . The wavelength converter of  claim 1 , wherein the wavelength-conversion loop is capable of down-converting the second wavelength to the first wavelength without using broadband components. 
     
     
         3 . The wavelength converter of  claim 1 , wherein the wavelength-conversion loop comprises a first wavelength conversion medium and a second wavelength conversion medium. 
     
     
         4 . The wavelength converter of  claim 3 , wherein the first wavelength-conversion medium is capable of converting the first wavelength to the second wavelength and converting the second wavelength to the first wavelength. 
     
     
         5 . The wavelength converter of  claim 4 , wherein the first wavelength-conversion medium comprises a non-linear medium. 
     
     
         6 . The wavelength converter of  claim 5 , wherein the first wavelength-conversion medium comprises periodically poled lithium niobate. 
     
     
         7 . The wavelength converter of  claim 3 , wherein the second wavelength-conversion medium is capable of converting the first wavelength to the second wavelength and converting the second wavelength to the first wavelength. 
     
     
         8 . The wavelength converter of  claim 7 , wherein the second wavelength-conversion medium comprises a non-linear medium. 
     
     
         9 . The wavelength converter of  claim 8 , wherein the second wavelength-conversion medium comprises periodically poled lithium niobate. 
     
     
         10 . The wavelength converter of  claim 1 , wherein:
 the signal comprises a first polarization component and a second polarization component, wherein both the first polarization component and the second polarization component have the first wavelength;   the first wavelength-conversion medium converts the first wavelength of the first polarization component to the second wavelength; and   the second wavelength-conversion medium converts the first wavelength of the second polarization component to the second wavelength.   
     
     
         11 . The wavelength converter of  claim 3 , wherein the first wavelength-conversion medium is capable of converting the first wavelength to the second wavelength and is capable of converting the second wavelength to a third wavelength. 
     
     
         12 . The wavelength converter of  claim 3 , wherein the second wavelength-conversion medium is capable of converting the first wavelength to the second wavelength and is capable of converting the second wavelength to a third wavelength. 
     
     
         13 . The wavelength converter of  claim 4 , wherein:
 the first wavelength-conversion medium converts the first wavelength to the second wavelength or converts the second wavelength to the first wavelength depending on a direction in which the signal travels through the first wavelength-conversion medium.   
     
     
         14 . The wavelength converter of  claim 7 , wherein:
 the second wavelength-conversion medium converts the first wavelength to the second wavelength or converts the second wavelength to the first wavelength depending on a direction in which the signal travels through the second wavelength-conversion medium.   
     
     
         15 . The wavelength converter of  claim 3 , wherein the wavelength-conversion loop comprises:
 a first portion where the signal has the first wavelength; and   a second portion where the signal has the second wavelength;   wherein the first portion and the second portion are separated by the first wavelength-conversion medium and the second wavelength-conversion medium.   
     
     
         16 . The wavelength converter of  claim 15 , wherein:
 the first portion of the wavelength-conversion loop is between the first wavelength-conversion medium and the second wavelength-conversion medium and is coupled to an input of the wavelength-conversion loop; and   the second portion of the wavelength-conversion loop is between the first wavelength-conversion medium and the second wavelength-conversion medium and is coupled to an output of the wavelength-conversion loop.   
     
     
         17 . The wavelength converter of  claim 1 , wherein:
 the signal having the first wavelength has a first polarization component and a second polarization component;   one of the first and second polarization components travels in a clockwise direction within the wavelength-conversion loop; and   the other one of the first and second polarization components travels in a counter-clockwise direction within the wavelength-conversion loop;   wherein the first and second polarization components travel within the same optical path.   
     
     
         18 . The wavelength converter of  claim 1 , wherein:
 the signal having the second wavelength has a first polarization component and a second polarization component;   one of the first and second polarization components travels in a clockwise direction within the wavelength-conversion loop; and   the other one of the first and second polarization components travels in a counter-clockwise direction within the wavelength-conversion loop;   wherein the first and second polarization components travel within the same optical path.