Tunable laser with directional coupler

A method for coupling silicon waveguides, the method comprising:

• guiding light into a first input of a directional coupler, wherein:
• the directional coupler has a shoulder;
• the directional coupler has a first ridge extending from the first input to a first output disposed on the shoulder;
• and
• the directional coupler has a second ridge extending from a second input to a second output disposed on the shoulder;
• guiding light from the first input to the first ridge;
• guiding light from the first ridge, through the shoulder to the second ridge, wherein the first ridge tapers to direct at least a portion of light, from the first input, out of the first ridge toward the second ridge;
• and
• guiding light from the second ridge to the second output.

A device for optically coupling waveguides, the device comprising:

• a first input;
• a second input;
• a first output;
• a second output;
• a shoulder disposed on a substrate;
• a first ridge disposed on the shoulder;
• and
• a second ridge disposed on the shoulder, wherein:
• the first ridge extends from the first input to the first output,
• the second ridge extends from the second input to the second output, and
• the first ridge tapers to direct at least a portion of light, from the first input, out of the first ridge toward the second ridge.

A device comprising:

• a first mirror;
• a second mirror;
• an optical coupler between the first mirror and the second mirror, the optical coupler comprising:
• a first input;
• a second input;
• a first output;
• a second output;
• a shoulder disposed on a substrate;
• a first ridge disposed on the shoulder;
• and
• a second ridge disposed on the shoulder, wherein:
• the first ridge extends from the first input to the first output,
• the second ridge extends from the second input to the second output, and
• the first ridge tapers to direct at least a portion of light, from the first input, out of the first ridge toward the second ridge.