Abstract: The present disclosure describes an optical system that uses a source optical signal to bias a receiver photodiode. The system includes an optical source, a receiver photodiode, a first biasing photodiode, a variable optical attenuator, and a compensation photodiode. The optical source produces a first optical signal. The receiver photodiode converts a second optical signal into an electrical signal. The first biasing photodiode generates a bias voltage for the receiver photodiode based on a first portion of the first optical signal. The variable optical attenuator produces a third optical signal based on (i) a second portion of the first optical signal and (ii) a portion of the electrical signal. The compensation photodiode passes the portion of the electrical signal based on the third optical signal.

Abstract: Embodiments herein describe an APD architecture that includes a silicon cap layer formed on top of a germanium layer (e.g., a Ge absorption region). The silicon cap layer can form a multiplication region of the APD. Moreover, a charge layer can be formed between the absorption region and the silicon cap layer (e.g., the multiplication region).

Abstract: In part, in one aspect, the disclosure relates to a photodiode. The photodiode may include a substrate; a semiconductor layer comprising an semiconductor material, the semiconductor layer disposed on the substrate and in communication with at least a region of the substrate, the semiconductor layer having a first side, a second side, and an upper surface, the semiconductor layer having a height; a semiconductor structure partially disposed on the upper surface, the semiconductor structure comprising at least one elongate portion that extends beyond the first side and along a portion of the upper surface of the semiconductor layer; and a metal contact that is in electrical connection with the elongate portion of the semiconductor structure.

Abstract: The present disclosure describes photodetectors with multiple inputs and methods of operating photodetectors with multiple inputs. An apparatus includes a substrate, an optical absorber, an optical device, and a tuner. The optical absorber is positioned on the substrate. The optical device produces a first optical signal and a second optical signal from an optical signal received at a first port of the optical device and directs the first optical signal and the second optical signal to the optical absorber. The tuner adjusts a first phase of the first optical signal and a second phase of the second optical signal such that a reflection of the first optical signal from the optical absorber destructively interferes with a reflection of the second optical signal from the optical absorber at the first port.

Abstract: The present disclosure describes photodetectors with multiple inputs and methods of operating photodetectors with multiple inputs. An apparatus includes a substrate, an optical absorber, and an optical device. The optical absorber is positioned on the substrate. The optical absorber includes a first portion and a second portion coupled to the first portion along a line. The optical device produces a first optical signal and a second optical signal based on a received optical signal and directs the first optical signal through the first portion of the optical absorber in a direction substantially parallel to the line. The optical device also directs the second optical signal through the second portion of the optical absorber in the direction substantially parallel to the line.

Abstract: A photodetector and method of making a photodetector are disclosed. An apparatus includes a semiconductor disk, a first doped region, and a first absorption region. The first doped region is disposed within the semiconductor disk such that the first doped region extends across a center of the semiconductor disk. The first doped region has a first doping type. The first absorption region is disposed on the first doped region such that a portion of the first doped region is positioned between the center of the semiconductor disk and the first absorption region along a radius of the semiconductor disk. The first absorption region includes a second doped region with a second doping type different from the first doping type. The first absorption region is arranged to absorb an optical signal as the optical signal travels along an inner circumference of the semiconductor disk.

Abstract: Embodiments herein described an optical system for testing the bandwidth of a photodiode (PD) in a photonic integrated circuit (PIC). In one embodiment, a first optical signal is provided to bias one or more PDs in the PIC which generate a DC bias (e.g., DC voltage) across the PD whose bandwidth is being tested. A second optical signal is directed to the PD being tested, thereby generating an AC signal. The second optical signal can be a tunable optical signal where its frequency/wavelength is varied to test the bandwidth of the PD. The AC signal generated by the PD being tested is passed through a heating element (e.g., a resistor) which generates heat. This heat is then measured by an interferometer. The output of the interferometer can be correlated to a bandwidth of the PD.

Abstract: A photodetector includes a substrate, an absorber, a first doped region, and a second doped region. The absorber includes a first region and a second region that is more heavily doped than the first region. The first doped region is positioned on the substrate such that the first doped region contacts the second region of the absorber. A portion of the first doped region is positioned between the absorber and the substrate. The second doped region is positioned on the substrate such that the second doped region contacts the first region of the absorber rather than the second region of the absorber. A portion of the second doped region is positioned between the absorber and the substrate. The portion of the second doped region extends across a majority of a width of the absorber.

Abstract: Embodiments herein describe an APD with a vertical electric field. In one embodiment, to reduce the thickness of the vertical electric field, an inversion layer at the interface between N doped silicon and an oxide is used as a cathode for the vertical electric field.

Abstract: Embodiments herein describe a germanium photodetector that can provide gain at low voltages. In one embodiment, the photodetector includes a P-type anode and a P-type cathode. In one embodiment, a germanium absorption region and a lighter-doped P-type region are disposed between the anode and cathode.

Abstract: Embodiments include a photonic device with a compensation structure. The photonic device includes a waveguide with a refractive index which changes according to the thermo-optic effect as a temperature of the photonic device fluctuates. The compensation structure is positioned on the photonic device to counteract or otherwise alter the thermo-optic effect on the refractive index of the waveguide in order to prevent malfunctions of the photonic device.

Abstract: A method includes providing a photonic wafer that includes an electrical layer and a layer disposed on a substrate. The layer includes at least one optical waveguide that is disposed between the electrical layer and the substrate. The method also includes removing a portion of the substrate underneath the at least one optical waveguide and forming an end-face coupler. A portion of the end-face coupler is within the removed portion of the substrate. The end-face coupler transmits an optical signal to, or receives an optical signal from, an external optical device.

Abstract: A photodetector includes a substrate, a first optical absorber, and a second optical absorber. The first optical absorber is disposed in the substrate along a direction of propagation of an optical signal through the substrate. The first optical absorber is offset in the substrate according to an offset of the optical signal in a direction orthogonal to the direction of propagation. The second optical absorber is disposed in the substrate along the direction of propagation of the optical signal. The second optical absorber is offset in the substrate according to the offset of the optical signal in the direction orthogonal to the direction of propagation.

Abstract: A photodetector includes a substrate, an optical absorber, a first doped region, a second doped region, and a third doped region. The optical absorber is disposed in the substrate and includes a first region and a second region. The first doped region is disposed in the substrate such that the first doped region contacts the second region of the optical absorber. The second doped region is disposed in the substrate such that the second doped region contacts the second region of the optical absorber. The second region of the optical absorber is positioned between the first doped region and the second doped region. The third doped region is disposed in the substrate and has an opposite doping relative to the first doped region and the second doped region. The first region of the optical absorber is positioned between the third doped region and the second region of the optical absorber.

Abstract: Methods and systems for a vertical junction high-speed phase modulator are disclosed and may include a semiconductor device having a semiconductor waveguide including a slab section, a rib section extending above the slab section, and raised ridges extending above the slab section on both sides of the rib section. The semiconductor device has a vertical pn junction with p-doped material and n-doped material arranged vertically with respect to each other in the rib and slab sections. The rib section may be either fully n-doped or p-doped in each cross-section along the semiconductor waveguide. Electrical connection to the p-doped and n-doped material may be enabled by forming contacts on the raised ridges, and electrical connection may be provided to the rib section from one of the contacts via periodically arranged sections of the semiconductor waveguide, where a cross-section of both the rib section and the slab section in the periodically arranged sections may be fully n-doped or fully p-doped.

Abstract: Embodiments include a photonic device with a compensation structure. The photonic device includes a waveguide with a refractive index which changes according to the thermo-optic effect as a temperature of the photonic device fluctuates. The compensation structure is positioned on the photonic device to counteract or otherwise alter the thermo-optic effect on the refractive index of the waveguide in order to prevent malfunctions of the photonic device.

Abstract: Methods and systems for a vertical junction high-speed phase modulator are disclosed and may include a semiconductor device having a semiconductor waveguide including a slab section, a rib section extending above the slab section, and raised ridges extending above the slab section on both sides of the rib section. The semiconductor device has a vertical pn junction with p-doped material and n-doped material arranged vertically with respect to each other in the rib and slab sections. The rib section may be either fully n-doped or p-doped in each cross-section along the semiconductor waveguide. Electrical connection to the p-doped and n-doped material may be enabled by forming contacts on the raised ridges, and electrical connection may be provided to the rib section from one of the contacts via periodically arranged sections of the semiconductor waveguide, where a cross-section of both the rib section and the slab section in the periodically arranged sections may be fully n-doped or fully p-doped.

Abstract: Methods and systems for selectively illuminated integrated photodetectors with configured launching and adaptive junction profile for bandwidth improvement may include a photonic chip comprising an input waveguide and a photodiode. The photodiode comprises an absorbing region with a p-doped region on a first side of the absorbing region and an n-doped region on a second side of the absorbing region. An optical signal is received in the absorbing region via the input waveguide, which is offset to one side of a center axis of the absorbing region; an electrical signal is generated based on the received optical signal. The first side of the absorbing region may be p-doped. P-doped and n-doped regions may alternate on the first and second sides of the absorbing region along the length of the photodiode. The absorbing region may comprise germanium, silicon, silicon/germanium, or similar material that absorbs light of a desired wavelength.

Abstract: A method includes providing a photonic wafer that includes an electrical layer and a layer disposed on a substrate. The layer includes at least one optical waveguide that is disposed between the electrical layer and the substrate. The method also includes removing a portion of the substrate underneath the at least one optical waveguide and forming an end-face coupler. A portion of the end-face coupler is within the removed portion of the substrate. The end-face coupler transmits an optical signal to, or receives an optical signal from, an external optical device.

Abstract: A method includes providing a photonic wafer that includes an electrical layer and a layer disposed on a substrate. The layer includes at least one optical waveguide that is disposed between the electrical layer and the substrate. The method also includes removing a portion of the substrate underneath the at least one optical waveguide and forming an end-face coupler. A portion of the end-face coupler is within the removed portion of the substrate. The end-face coupler transmits an optical signal to, or receives an optical signal from, an external optical device.