Patent ID: 8086111

Claim:
An apparatus for use in an optical transmitter (TX) for controlling an optical output power level of at least one laser of the optical TX, the apparatus comprising: a signal transition detection (XD) circuit electrically coupled to input circuitry of the optical TX, the signal XD circuit detecting whether an input data signal to the optical TX has transitioned from a logic 0 to a logic 1, or vice versa, within a predetermined timing interval and producing an XD output signal; and an optical output power monitoring feedback loop, the feedback loop comprising: at least one monitor photodetector, the photodetector receiving at least a portion of an optical output signal produced by a corresponding laser of the optical TX and producing an electrical monitor signal based on the optical output signal; an electrical detection circuit configured to receive the electrical monitor signal produced by the monitor photodetector and to produce an electrical detection signal based on the electrical monitor signal; a bandwidth-selectable (BW-S) lowpass filter (LPF) configured to receive the electrical detection signal produced by the electrical detection circuit and to filter the electrical detection signal to produce an electrical filtered signal; a power monitoring circuit (PMC) configured to receive the electrical filtered signal produced by the BW-S LPF and to produce an electrical average power signal based on the electrical filtered signal, the electrical average power signal corresponding to a measure of an average optical output power level of the optical output signal produced by the laser; and a controller device electrically coupled to the PMC and to the signal XD circuit, the controller device being configured to perform an optical output power control system (OPCS) algorithm that controls the optical output power level of the laser based at least in part on the electrical average power signal produced by the PMC and on the XD output signal produced by the signal XD circuit.