Abstract: A waveguide mode expander couples a smaller optical mode in a semiconductor waveguide to a larger optical mode in an optical fiber. The waveguide mode expander comprises a shoulder and a ridge. In some embodiments, the ridge of the waveguide mode expander has a plurality of stages, the plurality of stages having different widths at a given cross section.

Abstract: A waveguide coupler includes a first waveguide and a second waveguide. The waveguide coupler also includes a connecting waveguide disposed between the first waveguide and the second waveguide. The connecting waveguide includes a first material having a first index of refraction and a second material having a second index of refraction higher than the first index of refraction.

Abstract: Micro pillars are formed in silicon. The micro pillars are used in boding the silicon to hetero-material such as III-V material, ceramics, or metals. In bonding the silicon to the hetero-material, indium is used as a bonding material and attached to the hetero-material. The bonding material is heated and the silicon and the hetero-material are pressed together. As the silicon and the hetero-material are pressed together, the micro pillars puncture the bonding material. In some embodiments, pedestals are used in the silicon as hard stops to align the hetero-material with the silicon.

Abstract: A photonics system includes a transmit photonics module and a receive photonics module. The photonics system also includes a transmit waveguide coupled to the transmit photonics module, a first optical switch integrated with the transmit waveguide, and a diagnostics waveguide optically coupled to the first optical switch. The photonics system further includes a receive waveguide coupled to the receive photonics module and a second optical switch integrated with the receive waveguide and optically coupled to the diagnostics waveguide.

Abstract: A composite semiconductor laser is made by securing a III-V wafer to a transfer wafer. A substrate of the III-V wafer is removed, and the III-V wafer is etched into a plurality of chips while the III-V wafer is secured to the transfer wafer. The transfer wafer is singulated. A portion of the transfer wafer is used as a handle for bonding the chip in a recess of a silicon device. The chip is used as a gain medium for the semiconductor laser.

Abstract: A tunable laser has a first mirror, a second mirror, a gain medium, and a directional coupler. The first mirror and the second mirror form an optical resonator. The gain medium and the directional coupler are, at least partially, in an optical path of the optical resonator. The first mirror and the second mirror comprise binary super gratings. Both the first mirror and the second mirror have high reflectivity. The directional coupler provides an output coupler for the tunable laser.

Abstract: An optical filter for attenuating higher-order modes in an optical waveguide includes a shoulder slab formed of a first material having a first index of refraction and disposed on a second material having a second index of refraction, the first index of refraction being higher than the second index of refraction. The shoulder slab defines a near end having a first width, an intermediate section, adjacent to the first end section, and a far end section, adjacent to the intermediate section and opposite the first end section along a direction of beam propagation. The optical filter also includes a waveguide ridge, formed of the first material and disposed atop the shoulder slab, that traverses the shoulder slab, and is configured to guide light of a fundamental mode along the direction of beam propagation from the near end section to the far end section.

Abstract: A device for optical communication is described. The device comprises two transceivers integrated on one chip. A first transceiver can be used with existing optical-communication architecture. As a more advanced optical-communication architecture becomes adopted, the device can be switched from using the first transceiver to using a second transceiver to communicate using the more advanced optical-communication architecture.

Abstract: A device for a gain medium for a semiconductor laser has an active region, a buffer layer, a substrate, and an etch stop between the buffer layer and the substrate. The device is bonded to a silicon platform having silicon devices, such as a waveguide and mirror. The substrate is removed, after bonding the device to the platform. The buffer layer is made of different material than the substrate to reduce undercut of the buffer layer during substrate removal compared to a buffer layer made of the same material as the substrate.

Abstract: A photonic device includes a semiconductor wafer having a waveguide formed therein. An end of the waveguide includes a step. The photonic device further includes a semiconductor chip bonded to the semiconductor wafer and having an active region, and a waveguide coupler disposed in a gap between a sidewall of the semiconductor chip and the end of the waveguide. The waveguide coupler includes an optical bridge that has a first end and a second end opposing the first end. The first end of the optical bridge is interfaced with a facet of the active region of the semiconductor chip. The second end of the optical bridge is interfaced with the end of waveguide, and has a portion thereof disposed over the step at the end of the waveguide.

Abstract: A waveguide coupler has a compression region and an expansion region for coupling light between a silicon waveguide and an optical fiber. The compression region receives light from the silicon waveguide and compresses an optical mode of the light. Light is transmitted from the compression region to an expansion region. The expansion region expands the light to have a larger cross section. Light is then transmitted to the optical fiber.

Abstract: An integrated non-reciprocal polarization rotator comprises a substrate, a Faraday crystal, a first waveguide, and a second waveguide. The substrate has a recess extending to a predetermined depth. The Faraday crystal is mounted in the recess and optically coupled with the first waveguide and the second waveguide.

Abstract: A method of operating a BPSK modulator includes receiving an RF signal at the BPSK modulator and splitting the RF signal into a first portion and a second portion that is inverted with respect to the first portion. The method also includes receiving the first portion at a first arm of the BPSK modulator, receiving the second portion at a second arm of the BPSK modulator, applying a first tone to the first arm of the BPSK modulator, and applying a second tone to the second arm of the BPSK modulator. The method further includes measuring a power associated with an output of the BPSK modulator and adjusting a phase applied to at least one of the first arm of the BPSK modulator or the second arm of the BPSK modulator in response to the measured power.

Abstract: An optical receiver, used in wavelength-division multiplexing, has multiple photodetectors per channel. The optical receiver comprises a demultiplexer to separate incoming light into different output waveguides, one output waveguide for each channel. A splitter is used in each output waveguide to split each output waveguide into two or more branches. A separate photodetector is coupled with each branch so that two or more photodetectors are used to measure each channel.

Abstract: A waveguide mode expander couples a smaller optical mode in a semiconductor waveguide to a larger optical mode in an optical fiber. The waveguide mode expander comprises a shoulder and a ridge. In some embodiments, the ridge of the waveguide mode expander has a plurality of stages, the plurality of stages having different widths at a given cross section.

Abstract: A photonics system includes a transmit photonics module and a receive photonics module. The photonics system also includes a transmit waveguide coupled to the transmit photonics module, a first optical switch integrated with the transmit waveguide, and a diagnostics waveguide optically coupled to the first optical switch. The photonics system further includes a receive waveguide coupled to the receive photonics module and a second optical switch integrated with the receive waveguide and optically coupled to the diagnostics waveguide.

Abstract: A method forms a vertical output coupler for a waveguide, formed of waveguide material and disposed within a layer stack on a top surface of a wafer. The method includes etching through a portion of the wafer to form a via that exposes the waveguide material, and etching the waveguide material to remove at least a first portion of the waveguide. The etching forms a tilted plane in the waveguide material. The method further includes coating the first tilted plane with one or more reflective layers, to form a tilted mirror in contact with the first tilted plane in the waveguide material. The tilted mirror forms the vertical output coupler such that light propagating through the waveguide is deflected by the tilted mirror, and exits the waveguide.

Abstract: A reflective structure includes an input/output port and an optical splitter coupled to the input/output port. The optical splitter has a first branch and a second branch. The reflective structure also includes a first resonant cavity optically coupled to the first branch of the optical splitter. The first resonant cavity comprises a first set of reflectors and a first waveguide region disposed between the first set of reflectors. The reflective structures further includes a second resonant cavity optically coupled to the second branch of the optical splitter. The second resonant cavity comprises a second set of reflectors and a second waveguide region disposed between the second set of reflectors.

Abstract: A v-groove assembly is used to edge couple a lensed fiber (e.g., an optical fiber made of silica) with a waveguide in a photonic chip. The v-groove assembly is made from fused silica. Fused silica is used to so that an adhesive (e.g., epoxy resin) used in bonding the lensed fiber to the v-groove assembly and/or bonding the v-groove assembly to the photonic chip can be cured, at least partially, by light.

Abstract: An optical filter for attenuating higher-order modes in an optical waveguide includes a shoulder slab formed of a first material having a first index of refraction and disposed on a second material having a second index of refraction, the first index of refraction being higher than the second index of refraction. The shoulder slab defines a near end having a first width, an intermediate section, adjacent to the first end section, and a far end section, adjacent to the intermediate section and opposite the first end section along a direction of beam propagation. The optical filter also includes a waveguide ridge, formed of the first material and disposed atop the shoulder slab, that traverses the shoulder slab, and is configured to guide light of a fundamental mode along the direction of beam propagation from the near end section to the far end section.