Patent ID: 9658476
Date: 2017-05-23
CPC Classifications: G02F

Claim:
1. A method of controlling a bias voltage supplied to an optical modulator, the modulator being configurable to be biased by application of the bias voltage such that the modulator operates at quadrature, the method comprising: providing, or determining that there is present, a stable optical input power to the modulator; providing a target for output power of the modulator, the target for the output power of the modulator being an output power corresponding to the modulator operating at quadrature; applying, to the modulator, a bias voltage having an initial value of zero volts; and thereafter, varying the bias voltage until the value of the bias voltage is the value that is closest to the initial value and that biases the modulator so that the output power of the modulator is within a pre-defined range of the target output power, wherein varying the bias voltage comprises, starting at the initial value, sweeping the bias voltage in a zigzag pattern with gradually increasing amplitude.