Patent ID: 8576888

Claim:
A method of controlling the power levels of an optical transmitter comprising: providing a first signal path for receiving and filtering a transmit signal also used to control the optical transmitter, the first signal path including a first amplifier providing a first output representing a first logic state responsive to the transmit signal and a first level control signal, and a second output representing a second logic state responsive to the transmit signal and a level control signal; providing a second signal path for receiving and filtering a signal from a monitor diode monitoring the emission of the optical transmitter; the transmit signal as filtered in the first signal path tracking a frequency response of the monitor diode signal as filtered in the second signal path; differentially comparing the outputs of a first differential peak detector, the upper excursions of the transmit signal as filtered in the first signal path and the monitor diode signal as filtered in the second signal path to create a first error signal, and differentially comparing the outputs of a second differential peak detector, the lower excursions of the transmit signal as filtered in the first signal path and the monitor diode signal as filtered in the second signal path to create a second error signal; using the first and second error signals to adjust a high optical power level and a low optical power level of the optical transmitter to achieve a target average optical power level and extinction ratio.