Patent ID: 7426224

Claim:
A method for controlling an optical transmitter that includes a laser diode, a photodiode, a driver, and a control unit, the laser diode outputting an optical signal with a predetermined magnitude and a predetermined extinction ratio by receiving modulation and bias currents, the photodiode generating a monitored signal by receiving a portion of the optical signal, the driver controlling the laser diode, the control unit including a memory and a current controller, the memory storing a set of data for the modulation current in a set of addresses in connection with the bias current, the method comprising steps of: (a) monitoring the photocurrent to generate a monitored signal; (b) setting a first data for the bias current so as to maintain the monitored signal to be a predetermined level; (c) setting a second data for the modulation current by reading out from one of addresses in the memory in connection with the first data for the bias current; (d) providing a set of data including the first data and the second data to the driver from the control unit; and (e) providing the bias current and the modulation current each determined by the first data and second data, respectively, to the laser diode; wherein the optical transmitter further includes a low-pass-filter, and wherein the process for providing the set of data from the control unit to the driver is carried out through the low-pass-filter.