Abstract: Methods and systems for stabilized directional couplers are disclosed and may include a system comprising first and second directional couplers formed by first and second waveguides, where one of the waveguides may comprise a length extender between the directional couplers. The directional couplers may be formed by reduced spacing between the waveguides on opposite sides of the length extender. An input optical signal may be communicated into one of the waveguides, where at least a portion of the input optical signal may be coupled between the waveguides in the first directional coupler and at least a portion of the coupled optical signal may be coupled between the waveguides in the second directional coupler. Optical signals may be communicated out of the system with magnitudes at a desired percentage of the input optical signal. The length extender may add phase delay for signals in one of the first and second waveguides.

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: Methods and systems for grating couplers incorporating perturbed waveguides are disclosed and may include in a semiconductor photonics die, communicating optical signals into and/or out of the die utilizing a grating coupler on the die, where the grating coupler comprises perturbed waveguides. The perturbed waveguides may include rows of continuous waveguides with scatterers extending throughout a length of the perturbed waveguides a variable width along their length. The grating coupler may comprise a single polarization grating coupler comprising perturbed waveguides and a non-perturbed grating. The grating coupler may comprise a polarization splitting grating coupler (PSGC) that includes two sets of perturbed waveguides at a non-zero angle, or a plurality of non-linear rows of discrete shapes. The PSGC may comprise discrete scatterers at an intersection of the sets of perturbed waveguides. The grating coupler may comprise individual scatterers between the perturbed waveguides.

Abstract: Systems and methods for a focused field avalanche photodiode (APD) may include an absorbing layer, an anode, a cathode, an N-doped layer, a P-doped layer, and a multiplication region between the N-doped layer and the P-doped layer. Oxide interfaces are located at top and bottom surfaces of the anode, cathode, N-doped layer, P-doped layer, and multiplication region. The APD may absorb an optical signal in the absorbing layer to generate carriers, and direct them to a center of the cathode using doping profiles in the N-doped layer and the P-doped layer that vary in a direction perpendicular to the top and bottom surfaces. The doping profiles in the N-doped layer and the P-doped layer may have a peak concentration midway between the oxide interfaces, or the N-doped layer may have a peak concentration midway between the oxide interfaces while the P-doped layer may have a minimum concentration there.

Abstract: Methods and systems for an all-optical wafer acceptance test may include an optical transceiver on a chip, the optical transceiver comprising first, second, and third grating couplers, an interferometer comprising first and second phase modulators, a splitter, and a plurality of photodiodes. A first input optical signal may be received in the chip via the first grating coupler, where the first input optical signal may be coupled to the interferometer. An output optical signal may be coupled out of the chip via the second grating coupler for a first measurement of the interferometer. A second input optical signal may be coupled to a third grating coupler and a portion of the second input optical signal may be communicated to each of the plurality of photodiodes via the splitter. A voltage may be generated using the photodiodes based on the second input signal that may bias the first phase modulator.

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: Methods and systems for large silicon photonic interposers by stitching are disclosed and may include, in an optical communication system including a silicon photonic interposer, where the interposer includes a plurality of reticle sections: communicating an optical signal between first and second reticle sections utilizing a waveguide. The waveguide may include a taper region at a boundary between the two reticle sections, the taper region expanding an optical mode of the communicated optical signal prior to the boundary and narrowing the optical mode after the boundary. A continuous wave (CW) optical signal may be received in a first of the reticle sections from an optical source external to the interposer. The CW optical signal may be received in the interposer from an optical source assembly coupled to a grating coupler in the first of the reticle sections in the silicon photonic interposer.

Abstract: Methods and systems for mode converters for grating couplers may include a photonic chip comprising a waveguide, a grating coupler, and a mode converter, with the waveguide being coupled to the grating coupler via the mode converter. The mode converter may include waveguide material and tapers defined by triangular regions, where the triangular regions do not have waveguide material. The photonic chip may receive an optical signal in the mode converter from the waveguide, where the received optical signal has a light profile that may be spatially deflected in the mode converter to configure a desired profile in the grating coupler. A long axis of the tapers may be parallel to a direction of travel of the optical signal. The long axis of the tapers may point towards the input waveguide of the grating couplers, which may be linear.

Abstract: A system for integrated power combiners is disclosed and may include receiving optical signals in input optical waveguides and phase-modulating the signals to configure a phase offset between signals received at a first optical coupler, where the first optical coupler may generate output signals having substantially equal optical powers. Output signals of the first optical coupler may be phase-modulated to configure a phase offset between signals received at a second optical coupler, which may generate an output signal having an optical power of essentially zero and a second output signal having a maximized optical power. Optical signals received by the input optical waveguides may be generated utilizing a polarization-splitting grating coupler to enable polarization-insensitive combining of optical signals. Optical power may be monitored using optical detectors. The monitoring of optical power may be used to determine a desired phase offset between the signals received at the first optical coupler.

Abstract: Methods and systems for a low-parasitic silicon high-speed phase modulator are disclosed and may include in an optical phase modulator that comprises a PN junction waveguide formed in a silicon layer, wherein the silicon layer may be on an oxide layer and the oxide layer may be on a silicon substrate. The PN junction waveguide may have fingers of p-doped and n-doped regions on opposite sides along a length of the PN junction waveguide. Contacts may be formed on the fingers of p-doped and n-doped regions. The fingers of p-doped and n-doped regions may be arranged symmetrically about the PN junction waveguide or staggered along the length of the PN junction waveguide. Etch transition features may be removed along the p-doped and n-doped regions.

Abstract: Methods and systems for large silicon photonic interposers by stitching are disclosed and may include, in an optical communication system including a silicon photonic interposer, where the interposer includes a plurality of reticle sections: communicating an optical signal between first and second reticle sections utilizing a waveguide. The waveguide may include a taper region at a boundary between the two reticle sections, the taper region expanding an optical mode of the communicated optical signal prior to the boundary and narrowing the optical mode after the boundary. A continuous wave (CW) optical signal may be received in a first of the reticle sections from an optical source external to the interposer. The CW optical signal may be received in the interposer from an optical source assembly coupled to a grating coupler in the first of the reticle sections in the silicon photonic interposer.

Abstract: Methods and systems for a vertical junction high-speed phase modulator are disclosed and may include a semiconductor waveguide including a slab section, a rib section extending above the slab section, raised ridges extending above the slab section on both sides of the rib section, and 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 fully p-doped in each cross-section along the semiconductor waveguide. Electrical contact may be made to the doped material via contacts on the raised ridges, and electrical contact may be made to the rib section via periodically arranged sections of the semiconductor waveguide. A cross-section of both the rib section and the slab section in the periodically arranged sections may be mostly n-doped with an undoped portion or mostly p-doped with an undoped portion.

Abstract: Methods and systems for a silicon-based optical phase modulator with high modal overlap may include, in an optical modulator having a rib waveguide in which a cross-shaped depletion region separates four alternately doped sections: receiving an optical signal at one end of the optical modulator, modulating the received optical signal by applying a modulating voltage, and communicating a modulated optical signal out of an opposite end of the modulator. The modulator may be in a silicon photonically-enabled integrated circuit which may be in a complementary-metal oxide semiconductor (CMOS) die. An optical mode may be centered on the cross-shaped depletion region. The four alternately doped sections may include: a shallow depth p-region, a shallow depth n-region, a deep p-region, and a deep n-region. The shallow depth p-region may be electrically coupled to the deep p-region periodically along the length of the modulator.

Abstract: The present disclosure provides for two-dimensional mode matching by receiving an optical signal traveling in a first direction; and scattering the optical signal according to a scattering strength that progressively changes in the first direction. In various embodiments, the scattering strength progressively changes by increasing or decreasing in the first direction. A plurality of scatterers disposed in a path of the optical signal change in widths that progressively increase or decrease along the first direction. In various embodiments, a second optical signal is received in the grating coupler from a second direction; and is scattered into a surface of a photonic chip via a grating coupler. In some embodiments, the second direction is perpendicular to the first direction.

Abstract: Methods and systems for mode converters for grating couplers may include a photonic chip comprising a waveguide, a grating coupler, and a mode converter, with the waveguide being coupled to the grating coupler via the mode converter. The mode converter may include waveguide material and tapers defined by tapered regions, where the tapered regions do not have waveguide material. The photonic chip may receive an optical signal in the mode converter from the waveguide, where the received optical signal has a light profile that may be spatially deflected in the mode converter to configure a desired profile in the grating coupler. A long axis of the tapers may be parallel to a direction of travel of the optical signal. The long axis of the tapers may point towards the input waveguide of the grating couplers, which may be linear.

Abstract: Methods and systems for a low-parasitic silicon high-speed phase modulator are disclosed and may include in an optical phase modulator that comprises a PN junction waveguide formed in a silicon layer, wherein the silicon layer may be on an oxide layer and the oxide layer may be on a silicon substrate. The PN junction waveguide may have fingers of p-doped and n-doped regions on opposite sides along a length of the PN junction waveguide. Contacts may be formed on the fingers of p-doped and n-doped regions. The fingers of p-doped and n-doped regions may be arranged symmetrically about the PN junction waveguide or staggered along the length of the PN junction waveguide. Etch transition features may be removed along the p-doped and n-doped regions.

Abstract: Methods and systems for two-dimensional mode-matching grating couplers may include in a photonic chip comprising a grating coupler at a surface of the photonic chip, where the grating coupler has increased scattering strength in a direction of a light wave traveling through the grating coupler: receiving an optical signal from a first direction within the photonic chip; and scattering the optical signal out of the surface of the photonic chip. A second optical signal may be received in the grating coupler from a second direction within the photonic chip. The second optical signal may be scattered out of the surface of the photonic chip. The increasing scattering strength may be caused by increased width scatterers along a direction perpendicular to the direction of light travel. The increased scattering strength may be caused by a transition of shapes of scatterers in the grating coupler.

Abstract: Methods and systems for an all-optical wafer acceptance test may include an optical transceiver on a chip, the optical transceiver comprising first, second, and third grating couplers, an interferometer comprising first and second phase modulators, a splitter, and a plurality of photodiodes. A first input optical signal may be received in the chip via the first grating coupler, where the first input optical signal may be coupled to the interferometer. An output optical signal may be coupled out of the chip via the second grating coupler for a first measurement of the interferometer. A second input optical signal may be coupled to a third grating coupler and a portion of the second input optical signal may be communicated to each of the plurality of photodiodes via the splitter. A voltage may be generated using the photodiodes based on the second input signal that may bias the first phase modulator.

Abstract: Methods and systems for silicon photonics wavelength division multiplexing transceivers are disclosed and may include, in a transceiver integrated in a silicon photonics chip: generating a first modulated output optical signal at a first wavelength utilizing a first electrical signal, generating a second modulated output optical signal at a second wavelength utilizing a second electrical signal, communicating the first and second modulated output optical signals into an optical fiber coupled to the chip utilizing a multiplexing grating coupler in the chip. A received input optical signal may be split into a modulated input optical signal at the first wavelength and a modulated input optical signal at the second wavelength utilizing a demultiplexing grating coupler in the chip. The first and second modulated input optical signals may be converted to first and second electrical input signals utilizing first and second photodetectors in the chip.