SIMPLIFIED EXTINCTION RATIO CONTROL FOR MULTIPLE MACH-ZEHNDER INTERFEROMETER MODULATORS
Disclosed herein are methods, structures, apparatus and devices that improve the control and/or controllability of a group of Mach-Zehnder Interferometer modulators. Advantageously, such control may be implemented with optical tuning elements shared among all of the modulators, or with separate optical tuning elements operated through the effect of a set of common signals. Accordingly implementations according to one aspect of the present disclosure provides a significantly simplified configuration—where the extinction ratios of all modulators within the group are controlled jointly—in sharp contrast to those configuration(s) wherein all modulators are individually controlled.
1 . A method for controlling the operation of a group of Mach-Zehnder Interferometer (MZI) modulators, said group of MZI modulators having a common input and a common output, said method comprising:
providing and optically connecting a single tunable splitter to an input stage of the group of MZI modulators, wherein two output branches of the tunable splitter are directed to subsequent stages of fixed splitting, such that outputs from the subsequent stages are routed to form the group MZI modulators, each individual modulator comprising the group having a top arm and a bottom arm, and configured such that the top arm of each modulator in the group is optically connected to the one of the tunable splitter output branches, while the bottom arm of each modulator is optically connected to the other one of the tunable splitter output branches.
2 . An optical structure exhibiting a simplified extinction ratio control for multiple Mach-Zehnder Interferometer (MZI) modulators comprising:
a plurality of MZI modulators configured in parallel such that they share a common input and a common output;
wherein each one of said plurality of MZI modulators includes a tunable power splitter;
said optical structure configured such that a single common control signal drives all of the power splitters