OPTIMUM MODULATOR BIAS SYSTEMS AND METHODS IN COHERENT OPTICAL TRANSMITTERS

摘要

A modulator bias selection method, a coherent optical transmitter, and optical modulator solve the problem of generating a correct constellation using the bias points with the minimum phase adjustment range. The optimum modulator bias systems and methods include a coherent optical transmitter with control of four (XI, XQ, YI, YQ) quadrature data signals via a transmitter (Tx) application specific integrated circuit (ASIC), with a modulator bias controller which implements an algorithm to find the optimum bias points. The optimum bias points yield a correct constellation with minimum phase/bias adjustment. An algorithm is used to find the optimum bias solution using fast, simple method, adjusting only one quadrature at a time and exploiting a control feature of the Tx ASIC. This algorithm is significantly simpler than a generalized search, is a local algorithm, and uses only DC power measurement at the transmitter.

主权项

1. A modulator bias selection method, comprising:
for each pair of inner phase adjusters of an optical modulator, selecting a minimum bias point by sweeping a left phase adjuster and a right phase adjuster of each of the inner phase adjusters to find the minimum bias point; for each pair of outer phase adjusters, selecting a half-power bias point by separately sweeping a left phase adjuster and a right phase adjuster of each of the outer phase adjusters to find the half-power bias point; and setting the pair of inner phase adjusters and the pair of outer phase adjusters based on the selecting steps, wherein the modulator bias selection method comprises a local algorithm.