Patent ID: 7853155
Filing Date: 2010-12-14
Classification: G02F,H04B

Abstract:
1. A method of operating an optical transmitter for transmission of an optical signal over a dispersive fiber optic media to a remote receiver comprising: providing an initial bias level of a first RF signal and a second RF signal respectively to an optical modulator for modulating an optical signal input to the optical modulator; determining the amplitude of an optical signal output of the optical modulator operating at the provided initial bias levels; adjusting the bias level of at least one of the first and second RF signals based upon a determined output level and an expected output level at a configuration set point for the respective initial bias levels; determining the expected output level from a lookup table based upon the provided respective initial bias levels; adjusting the bias levels using a first software program sequence for making coarse bias adjustment on start up of the optical transmitter, and using a second software program sequence for making a fine bias adjustment; adjusting the bias level of only one of the RF signals during the first software program sequence; incrementing the bias level of said one RF signal during the first software program sequence and averaging the output level of the modulator over a program controlled time period; determining whether the first RF input signal should be incremented or decremented based upon the change in the output level of the optical modulator as a result of incrementing the first RF input signal; when the lookup table indicates the first RF signal is to be incremented, then incrementing the first RF signal by a computed delta value and comparing a resulting output to a first threshold value; when the lookup table indicates that the first RF signal is to be decremented, then decrementing the first RF signal by the delta value until a subsequently averaged output signal exceeds the first threshold value; determining when the subsequently averaged output signal exceeds the first threshold value then activating the second program sequence for more finely adjusting the bias level of both the first RF signal and the second RF signal; adjusting the bias level of the first RF signal during the second program sequence if a current output value T adjusting the bias level of the second RF signal during the second program sequence if a current output value T