An exemplary multi quantum well structure may include a silicon platform having a pit formed in the silicon platform, a chip positioned inside the pit, a first waveguide formed in the chip, and a second waveguide formed in the silicon platform. The pit may be defined at least in part by a sidewall and a base. The chip may include a first side and a first recess in the first side. The first side may be defined in part by a first cleaved or diced facet. The first recess may be defined in part by a first etched facet. The first waveguide may be configured to guide an optical beam to pass through the first etched facet. The second waveguide may be configured to guide the optical beam to pass through the sidewall. The second waveguide may be optically aligned with the first waveguide.

A III-V semiconductor waveguide nanoridge structure having a narrow supporting base with a freestanding wider body portion on top, is disclosed. In one aspect, the III-V waveguide includes a PIN diode. The waveguide comprises a III-V semiconductor waveguide core formed in the freestanding wider body portion; at least one heterojunction incorporated in the III-V semiconductor waveguide core; a bottom doped region of a first polarity positioned at a bottom of the narrow supporting base, forming a lower contact; and an upper doped region of a second polarity, forming an upper contact. The upper contact is positioned in at least one side wall of the freestanding wider body portion.

A germanium waveguide is formed from a P-type silicon substrate that is coated with a heavily-doped N-type germanium layer and a first N-type doped silicon layer. Trenches are etched into the silicon substrate to form a stack of a substrate strip, a germanium strip, and a first silicon strip. This structure is then coated with a silicon nitride layer.

A grating coupler having first and second ends for coupling a light beam to a waveguide of a chip includes a substrate configured to receive the light beam from the first end and transmit the light beam through the second end, the substrate having a first refractive index n1, a grating structure having curved grating lines arranged on the substrate, the grating structure having a second refractive index n1, wherein the curved grating lines have line width w and height d and are arranged by a pitch , wherein the second refractive index n2 is less than first refractive index n1, and a cladding layer configured to cover the grating structure, wherein the cladding layer has a third refractive index n3.

Systems and methods are provided for processing an optical signal. An example system may include a source disposed on a substrate and capable of emitting the optical signal. A first waveguide is formed in the substrate to receive the optical signal. A first coupler is disposed on the substrate to receive a reflected portion of the optical signal. A second waveguide is formed in the substrate to receive the reflected portion from the first coupler. A second coupler is formed in the substrate to mix the optical signal and the reflected portion to form a mixed signal. Photodetectors are formed in the substrate to convert the mixed signal to an electrical signal. A processor is electrically coupled to the substrate and programmed to convert the electrical signal from a time domain to a frequency domain to determine a phase difference between the optical signal and the reflected portion.

Systems and methods are provided for processing an optical signal. An example system may include a source disposed on a substrate and capable of emitting the optical signal. A first waveguide is formed in the substrate to receive the optical signal. A first coupler is disposed on the substrate to receive a reflected portion of the optical signal. A second waveguide is formed in the substrate to receive the reflected portion from the first coupler. A second coupler is formed in the substrate to mix the optical signal and the reflected portion to form a mixed signal. Photodetectors are formed in the substrate to convert the mixed signal to an electrical signal. A processor is electrically coupled to the substrate and programmed to convert the electrical signal from a time domain to a frequency domain to determine a phase difference between the optical signal and the reflected portion.

A photonic integrated circuit platform includes a substrate, a first oxide layer disposed on the substrate and including an insulating transparent oxide, and a first optical element layer disposed on the first oxide layer and including a semiconductor material. The photonic integrated circuit platform further includes a second optical element layer disposed on the first optical element layer and including an insulating material different from the insulating transparent oxide of the first oxide layer, the second optical element layer further including a compound semiconductor material different from the semiconductor material of the first optical element layer, a second oxide layer disposed on the second optical element layer and including an insulating transparent oxide, and a plurality of optical elements formed by patterning the first optical element layer or the second optical element layer.

Examples described herein relate to an optical device with an integrated light-emitting structure to generate light and a waveguide integrated capacitor to monitor light. The light-emitting structure may emit light upon the application of electricity to the optical device. The waveguide integrated capacitor may be formed under the light-emitting structure to monitor the light emitted by the light-emitting structure. The waveguide integrated capacitor includes a waveguide region carrying at least a portion of the light. The waveguide region includes one or more photon absorption sites causing the generation of free charge carriers relative to an intensity of the light confined in the waveguide region resulting in a change in the conductance of the waveguide region.

Systems and methods are provided for processing an optical signal. An example system may include a source disposed on a substrate and capable of emitting the optical signal. A first waveguide is formed in the substrate to receive the optical signal. A first coupler is disposed on the substrate to receive a reflected portion of the optical signal. A second waveguide is formed in the substrate to receive the reflected portion from the first coupler. A second coupler is formed in the substrate to mix the optical signal and the reflected portion to form a mixed signal. Photodetectors are formed in the substrate to convert the mixed signal to an electrical signal. A processor is electrically coupled to the substrate and programmed to convert the electrical signal from a time domain to a frequency domain to determine a phase difference between the optical signal and the reflected portion.

A III-V semiconductor waveguide nanoridge structure having a narrow supporting base with a freestanding wider body portion on top, is disclosed. In one aspect, the III-V waveguide includes a PIN diode. The waveguide comprises a III-V semiconductor waveguide core formed in the freestanding wider body portion; at least one heterojunction incorporated in the III-V semiconductor waveguide core; a bottom doped region of a first polarity positioned at a bottom of the narrow supporting base, forming a lower contact; and an upper doped region of a second polarity, forming an upper contact. The upper contact is positioned in at least one side wall of the freestanding wider body portion.