Patent ID: 6873801

Claim:
An optical transmitter comprising: an optical element for outputting a first optical signal and a second optical signal indicative of a back-face output; an electronic absorption type external modulator connected to said optical element for modulating the first optical signal and for generating a modulated optical signal; an electronic absorption monitor connected to said electronic absorption type external modulator for monitoring electronic absorption of the modulated optical signal and generating an absorption value indicative of the monitored electronic absorption; an external modulator control unit connected to said electronic absorption monitor for determining a differential value between the absorption value and the second optical signal to control the modulated optical signal to a desired level, said external modulator control unit also generating an information signal including the differential value and indicative of operational parameters of said electronic absorption type external modulator; and an optical element control unit connected to said optical element and said external modulator control unit for controlling said optical element based upon the differential value and the second optical signal, wherein the first optical signal and the second optical signal are maintained at a constant level.