Optical wavelength converter and optical wavelength division multiplexing communication system using the same

An optical wavelength converter comprising:

• an optical-to-electrical converter for converting an optical signal into an electrical signal, having
• a first converter circuit for converting a first optical signal in a first optical wavelength into a first electrical signal,
• a waveform shaping circuit for limiting the first electric signal in amplitude to output an limited electrical signal,
• a series circuit including a coupling capacitor and a bias adjusting circuit provided after the coupling capacitor;
• an electrical-to-optical converter for converting the limited electrical signal into a second optical signal in a second optical wavelength;
• and
• a level converter provided between the optical-to-electrical converter and the electrical-to-optical converter for converting a level of the output of the electrical-to-optical converter to a signal having a level of the input of the electrical-to-optical converter.

An optical wavelength division multiplexing system comprising:

• a first optical wavelength converter for converting an optical signal in a first optical wavelength band into an optical signal in a second optical wavelength band, including;
• an optical-to-electrical converter for converting an input optical signal into an electric signal;
• an electrical-to-optical converter for converting an electric signal into an optical signal;
• and
• a duty control circuit connected between said optical-to-electrical converter and said electrical-to-optical converter for controlling the duty of the electric signal converted by the optical-to-electrical converter according to RZ/NRZ code information;
• multiplexing equipment for wave-multiplexing the optical signal in the second wavelength band converted from an optical signal in a first wavelength band by the optical wavelength converter;
• an optical fiber for transmitting the optical multi-wavelength signal multiplexed by the multiplexing equipment;
• demultiplexing equipment for demultiplexing said optical multi-wavelength signal transmitted through the optical fiber;
• and
• a second optical wavelength converter for converting the wavelength of the optical signal having the second wavelength band demultiplexed from said demultiplexing equipment into the optical signal having said first wavelength band.