Optical modulator utilizing unary encoding and auxiliary modulator section for load balancing

摘要

An optical modulator is configured to include multiple modulating sections formed along each arm and create a unary-encoded optical output signal by driving the number of sections required to represent the data value being transmitted (e.g., three sections driven to represent the data value “3”, four sections driven to represent the data value “4”). An auxiliary modulating section, isolated from the optical signal path, is included for creating a path for current flow in situations where only an odd number of modulating sections are required to represent the data. The activation of the auxiliary modulation section minimizes the current imbalance that would otherwise be present along a common node of the arrangement.

主权项

1. A silicon-based optical modulator for transmitting a unary-encoded digital data signal, the modulator comprising:
an input waveguiding section for receiving a continuous wave (CW) optical input signal; an input optical splitter, coupled to the output of the input waveguiding section for dividing the CW optical input signal into a pair of CW optical input signals; a pair of optical waveguides coupled to the outputs of the input optical splitter and forming a pair of modulator arms; a first plurality of N modulating sections disposed along a first modulator arm of the pair of modulator arms; a second plurality of N modulating sections disposed along a second, remaining modulator arm of the pair of modulator arms; a plurality of drivers, coupled to the first and second pluralities of N modulating sections, said plurality of drivers responsive to input signals representing a unary encoded data signal for selectively driving the pluralities of modulating sections to provide a predetermined phase shift to the pair of CW optical input signals propagating through the pair of modulator arms; an auxiliary modulating section that is isolated from the propagating CW optical input signals and that is coupled to an auxiliary driver, wherein the auxiliary driver selectively drives the auxiliary modulating section to reduce an electrical imbalance within the optical modulator; an output optical combiner for combining the pair of phase-shifted propagating optical input signals into a unary-encoded modulated optical output signal; and an output waveguiding section coupled to the output optical combiner for supporting the propagation of the unary-encoded modulated optical output signal.