Reducing back reflection in hybrid lasers

A hybrid laser comprising:

• a gain chip including a gain medium for generating and amplifying light;
• a first reflector optically coupled to the gain medium for reflecting at least a first portion of the light back through the gain medium;
• a photonic integrated circuit (PIC) chip comprising:
• an edge coupler for transmitting the light between the gain chip and a device layer on the PIC chip;
• a mode converter for converting a mode of the light to a mode providing less back reflection for light traveling back and forth within the PIC chip;
• a routing waveguide extending from the mode converter;
• a second reflector coupled to the routing waveguide for reflecting at least a second portion of the light back to the gain medium forming a laser cavity with the first reflector;
• and
• an output port coupled to the first or second reflector for outputting laser light;
• wherein the mode converter comprises a polarization rotator comprising a bent and tapered optical waveguide polarization rotator.

A hybrid laser comprising:

• a gain chip including a gain medium for generating and amplifying light;
• a first reflector optically coupled to the gain medium for reflecting at least a first portion of the light back through the gain medium;
• a photonic integrated circuit (PIC) chip comprising:
• an edge coupler for transmitting the light between the gain chip and a device layer on the PIC chip;
• a mode converter for converting a mode of the light to a mode providing less back reflection for light traveling back and forth within the PIC chip;
• a routing waveguide extending from the mode converter;
• a second reflector coupled to the routing waveguide for reflecting at least a second portion of the light back to the gain medium forming a laser cavity with the first reflector;
• and
• an output port coupled to the first or second reflector for outputting laser light;
• wherein the mode converter comprises a waveguide converter for converting a ridge waveguide to a bus waveguide;
• and
• wherein the routing waveguide comprises the a bus waveguide.