Optical transmitter module
To provide an optical transmitter module with simplified control of a voltage to be applied to an optical modulator. An optical transmitter module includes a semiconductor laser for irradiating a laser beam; a demultiplexer for branching the laser beam to output branched light beams; optical modulators for modulating an optical amplitude of each of the branched light beams into a first optical amplitude or a second optical amplitude, depending on an input level at two levels; and a multiplexer for multiplexing output light beams from the optical modulators. The optical transmitter module may include optical waveguides for connecting the optical modulators and the multiplexer, and the optical waveguides may include a first optical waveguide for causing a first phase difference and a second optical waveguide for causing a second phase difference different from the first phase difference.
1. An optical transmitter module, comprising:
a semiconductor laser for irradiating a laser beam;
a demultiplexer for branching the laser beam to output a plurality of branched light beams;
a plurality of optical modulators for modulating an optical amplitude of each of the plurality of branched light beams into a first optical amplitude or a second optical amplitude stronger than the first optical amplitude, depending on an input level at two levels; and
a multiplexer for multiplexing output light beams from the plurality of optical modulators,
wherein:
the demultiplexer is a multimode interferometer, and
the demultiplexer includes a first multimode interferometer for branching the laser beam to output an N number (N being an integer equal to or greater than three) of branched light beams, and a second multimode interferometer for multiplexing an M number (M being an integer equal to or greater than two,
wherein M<N) of branched light beams among the N number of branched light beams.
2. The optical transmitter module according to claim 1 , further comprising:
a plurality of optical waveguides for connecting the plurality of optical modulators and the multiplexer,
wherein the plurality of optical waveguides include:
a first optical waveguide for causing a first phase difference between an input port thereof and an output port thereof, and
a second optical waveguide for causing a second phase difference different from the first phase difference between an input port thereof and an output port thereof.
3. The optical transmitter module according to claim 1 , wherein the multiplexer includes a third multimode interferometer for multiplexing an N−M+1 number of output light beams into a single light beam.