Designs for lateral current control in optical amplifiers and lasers

A master oscillator power amplifier (MOPA) device configured to generate an output optical beam, the MOPA device comprising:

• a semiconductor laser section configured to generate laser light, the semiconductor laser comprising:
• a first reflector and a second optical reflector;
• a waveguide disposed between the first and the second optical reflectors, said waveguide including at least an active region configured to provide optical gain, the first optical reflector, the second optical reflector and the waveguide forming an active laser cavity;
• a semiconductor optical amplifier section disposed to receive the laser light via an input port to be guided therein, amplify at least a portion of said input light that is guided in the optical amplifier, and output at least a portion of said amplified light via an output port, the semiconductor optical amplifier comprising:
• an active waveguide extending in a longitudinal direction between the input port and the output port and having a waveguide width extending in a lateral direction between first and second lateral edges, wherein at least a portion of the active waveguide supports a plurality of lateral modes, and wherein the active waveguide comprises a gain layer configured to provide optical gain to light guided in said active waveguide;
• at least one electrode disposed with respect to the active waveguide to apply a voltage to said active waveguide, said at least one electrode comprising a conductive layer extending in the longitudinal direction and having a width extending in the lateral direction that that increases and decreases multiple times with position along the longitudinal direction, said at least one electrode having a first end closer to said input port than said output port and a second end closer to said output port than said input port, said first end having a smaller width than said second end.