OPTICAL TRANSMITTER

PURPOSE:To obtain an optical transmitter which produces a constant optical output at a constant extinction ratio independent of a change in ambient temperature of a laser diode. CONSTITUTION:An output change difference between the optical output of a laser diode 5 and the back optical output received by a photodiode 6 to a change in an ambient temperature is previously set by calculates 10 and 12 in an optical transmitter. The ambient temperature is detected by a temperature sensing device 7. The optical transmitter is so constituted as to compensate for a change in the optical output of the laser diode 5 to a temperature change, whereby the optical so that it produces a constant optical output at a constant extinction ratio.