Variable-width waveguide for semiconductor optical amplifier devices

An optical transmitter, comprising:

• a plurality of lasers configured to produce respective optical signals, each optical signal having a wavelength;
• optical components coupled to the plurality of lasers and configured to output a multiwavelength optical signal;
• and
• a semiconductor optical amplifier including a variable-width waveguide coupled to the optical components, the variable-width waveguide including:
• a plurality of narrow width regions;
• a plurality of wide width regions positioned alternately with the plurality of narrow width regions along a longitudinal axis of the waveguide, each of the narrow width regions having a width that is smaller than a width of each of the wide width regions;
• and
• a plurality of transition regions, each transition region positioned between adjacent ones of the narrow width regions and wide width regions, and each transition region having an adiabatically varying width;
• and
• optical components coupled to the variable-width waveguide, the optical components configured to receive a drive current and the waveguide having a reduced drive current density in the plurality of wide width regions.

A network device, comprising:

• electronic circuitry;
• and
• an optical transmitter coupled to the electronic circuitry, the optical transmitter including:
• one or more lasers configured to produce respective optical signals;
• optical components coupled to the one or more lasers;
• and
• a semiconductor optical amplifier coupled to the optical components, the semiconductor optical amplifier including:
• amplifying components configured to receive a drive current;
• and
• a variable-width waveguide including a plurality of narrow width regions and a plurality of wide width regions positioned alternately along a longitudinal axis of the waveguide, and a plurality of transition regions with each transition region positioned between adjacent ones of the narrow width regions and wide width regions and having an adiabatically varying width along the longitudinal axis, wherein the waveguide has reduced a drive current density due to the drive current in the plurality of wide width regions.