Patent ID: 6480329
Filing Date: 2002-11-12
Classification: H01S,H04B

Abstract:
An apparatus comprising:an optical amplifier which receives a WDM optical signal including a plurality of optical signals with different wavelengths and amplifies the WDM optical signal, comprising: an input port through which the WDM optical signal is received; a first monitor monitoring the received WDM optical signal, to thereby produce a first monitor signal; a first-stage optical amplifier which amplifies the received WDM optical signal and thereby outputs a first-stage amplified WDM optical signal; a first optical device which controls a level of the first-stage amplified WDM optical signal and thereby outputs a level controlled WDM optical signal; a second-stage optical amplifier which amplifies the level controlled WDM optical signal and thereby outputs a second-stage amplified WDM optical signal; a second monitor monitoring the second-stage amplified WDM optical signal, to thereby produce a second monitor signal; a second optical device which controls a spectrum of one of the first-stage amplified WDM optical signal, the level controlled WDM optical signal and the second-stage amplified WDM optical signal to compensate gain versus wavelength characteristics of the first-stage and second-stage optical amplifiers; and an output port through which the spectrum controlled second-stage amplified WDM optical signal is output as the amplified WDM optical signal, wherein the optical amplifier amplifies the WDM optical signal in accordance with one of the first monitor signal and the second monitor signal and outputs the amplified WDM optical signal.