Monolithic widely-tunable coherent receiver

A monolithic tunable polarization rotator comprising:

• a monocrystalline substrate;
• an optical splitter comprising an input waveguide and at least two output waveguides;
• a plurality electrodes disposed on each the at least two output waveguides, of the optical splitter, said plurality of electrodes configured to control an amplitude or a phase of the optical radiation propagating in the at least two output waveguides;
• and
• an optical coupler comprising at least one output waveguide, said optical coupler configured to receive input from the at least two output waveguides of the optical splitter.

A method of manufacturing a monolithically integrated optical receiver die, the method comprising:

• providing an input interface;
• providing at least one monocrystalline substrate;
• monolithically integrating a tunable laser resonator with the substrate, said tunable laser resonator comprising an output reflector and a tuning section, said tunable laser resonator configured to emit optical radiation from the output reflector along an optical axis, such that the wavelength of the emitted optical radiation is tunable over a wide wavelength range from between about 15 nm to about 100 nm, wherein the wide wavelength range is represented by Δλ/λ and is configured to be greater than a ratio Δn/n, wherein λ represents the wavelength of the optical radiation, Δλ represents the change in the wavelength of the optical radiation, n represents the refractive index of the tuning section, and Δn represents the change in the refractive index of the tuning section;
• monolithically integrating a first optical mixer with the substrate such that the first optical mixer is disposed at a distance less than approximately 750 μm from the input interface as measured along the optical axis, said first optical mixer having at least a first and a second input waveguide and a plurality of output waveguides, said first input waveguide of the first optical mixer optically connected to the laser resonator, said second input waveguide of the first optical mixer configured to receive a modulated optical signal from the input interface;
• monolithically integrating a second optical mixer with the substrate such that the second optical mixer is disposed at a distance less than approximately 750 μm from the input interface as measured along the optical axis, said second optical mixer having at least a first and a second input waveguide and a plurality of output waveguides, said first input waveguide of the second optical mixer optically connected to the laser resonator, said second input waveguide of the second optical mixer configured to receive a modulated optical signal from the input interface;
• monolithically integrating a polarization rotator with substrate, said polarization rotator arranged at an angle between about 20 deg and 160 deg or between about −20 deg and −160 deg with respect to the optical axis;
• and
• monolithically integrating a plurality of photo detectors with substrate, each of the plurality of photo detectors being optically connected to one of the plurality of output waveguides of the first or the second optical mixer.