Method and apparatus for wavelength conversion

A wavelength converter comprising:

• a demultiplexer, configured to demultiplex a wavelength division multiplexed (WDM) optical signal into at least two demultiplexed WDM optical signals, wherein a first demultiplexed WDM optical signal has a first frequency bandwidth and a second demultiplexed WDM optical signal has a second frequency bandwidth;
• a first wavelength converting section comprising a first conversion medium configured to receive said first demultiplexed WDM optical signal and an pump lightwave, wherein there is an interval between a said frequency of said pump lightwave and one frequency of said demultiplexed WDM optical signal with a frequency closest to said frequency of said pump lightwave. and said interval between said pump lightwave and said first demultiplexed WDM optical signal is equal to or greater than said first frequency bandwidth of said first demultiplexed WDM optical signal, and wherein a first output signal, including a first wavelength converted WDM optical signal, is produced at an output of said first wavelength converting section;
• a second wavelength converting section comprising a second conversion medium configured to receive said second demultiplexed WDM optical signal and a first and second pump lightwaves, wherein said second demultiplexed WDM optical signal is in a frequency bandwidth between a frequency of said first pump lightwave and an average frequency of said first and second pump lightwaves, wherein a frequency bandwidth between said first frequency of said first pump lightwave and said second demultiplexed WDM optical signal with a frequency closest to said first pump lightwave is set equal to or greater than said frequency bandwidth of said second demultiplexed WDM optical signal, and wherein a second output signal, including a second wavelength converted WDM optical signal, is produced at an output of said second wavelength converting section;
• a first filter, coupled to said first wavelength converting section, configured to receive said first output signal and to pass only said first wavelength converted WDM optical signal;
• a second filter, coupled to said second wavelength converting section, configured to receive said second output signal and to pass only said second wavelength converted WVDM optical signal;
• and
• a multiplexer, coupled to said first filter and said second filter, configured to multiplex said first wavelength converted WDM optical signal from said first filter and said second wavelength converted WDM optical signal from said second filter.

A system for wavelength conversion of an optical signal comprising:

• a conversion medium;
• an optical signal input to said conversion medium;
• at least one pump light source input to said conversion medium;
• a converted optical signal output from said conversion medium;
• and
• means for preventing noise produced by improper four wave mixing from appearing in a frequency band occupies by said converted optical signal.

A multifrequency light source comprising:

• N light sources;
• a multiplexer having said N light sources as an input and a multiplexed output;
• and
• a wavelength converter having said multiplexed output as an input and having 2N optical signal outputs.