Patent ID: 7437083

Claim:
A wavelength converter for binary optical signals, comprising: an interferometer structure, in particular a Mach-Zehnder interferometer, for generating an output signal by modulating a received local signal according to the modulation of a further received first input signal; a first pre-amplifier means for amplifying said first input signal before it is input into said interferometer structure; and a first control means for generating a first feedback signal to control the gain of said first pre-amplifier means in response to a first error signal derived from the output signal and representing the slope of the transfer function of the interferometer structure for the first input signal; with the interferometer structure operating in a differential mode additionally modulating the local signal according to the modulation of a received second input signal; a second pre-amplifier means providing for amplifying said second input signal before it is input to said interferometer structure; a second control means providing for generating a second feedback signal to control the gain of said second pre-amplifier means in response to a second error signal derived from the output signal and representing the slope of the transfer function of the interferometer structure for the second input signal; the first and the second control means interconnecting that the gain of each of the first and for the second pre-amplifier is controlled under consideration of both the first and the second error signal.