Drive circuit for electro-absorption modulator and optical transmitter employing the same

摘要

The present invention relates to an optical transmitter with a drive circuit that can stabilize a bias voltage of an optical modulator to realize long distance transmission by preventing degradation of waveform, even if there is a dispersion on a characteristic of an electro-absorption modulator according to temperature and a secular change. The drive circuit (J1, J6) supplies a driving voltage to a first electro-absorption modulator (EA2) which adsorbs a carrier light, depending on the driving voltage and outputting an intensity-modulated signal. A second modulator (EA1) is formed on the same chip as the first modulator (EA2). A current monitor (21) detects the optical current flowing the second modulator and a bias current supplying circuit (24) supplies a bias current to control the driving voltage according to a difference between the value of the optical current detected by the current member circuit (21) and a predetermined value.