Abstract: An optical device includes an optical reflector based on a coupled-loopback optical waveguide. In particular, an input port, an output port and an optical loop in arms of the optical reflector are optically coupled to a directional coupler. The directional coupler evanescently couples an optical signal between the arms. For example, the directional coupler may include: a multimode interference coupler and/or a Mach-Zehnder Interferometer (MZI). Moreover, destructive interference during the evanescent coupling determines the reflection and transmission power coefficients of the optical reflector.

Abstract: A standard-CMOS-process-compatible optical mode converter transitions an optical mode size using a series of adjacent regions having different optical mode sizes. In particular, in a partial-slab-mode region, which is adjacent to an initial rib-optical-waveguide-mode region, a width of a slab portion of the rib-type optical waveguide decreases and a width of a rib portion of the rib-type optical waveguide decreases to a first minimum tip size. Then, in a slab-mode region, which is adjacent to the partial-slab-mode region, the width of the slab portion decreases to a second minimum tip size. In addition, a dielectric layer is disposed over the slab portion, the rib portion and the BOX layer in the partial-slab-mode region, the slab portion and the BOX layer in the slab-mode region, and the BOX layer in a released-mode region that is adjacent to the slab-mode region and that does not include the semiconductor layer.

Abstract: A standard-CMOS-process-compatible optical mode converter transitions an optical mode size using a series of adjacent regions having different optical mode sizes. In particular, in a partial-slab-mode region, which is adjacent to an initial rib-optical-waveguide-mode region, a width of a slab portion of the rib-type optical waveguide decreases and a width of a rib portion of the rib-type optical waveguide decreases to a first minimum tip size. Then, in a slab-mode region, which is adjacent to the partial-slab-mode region, the width of the slab portion decreases to a second minimum tip size. In addition, a dielectric layer is disposed over the slab portion, the rib portion and the BOX layer in the partial-slab-mode region, the slab portion and the BOX layer in the slab-mode region, and the BOX layer in a released-mode region that is adjacent to the slab-mode region and that does not include the semiconductor layer.

Abstract: An optical modulator is described. This optical modulator may be implemented using silicon-on-insulator (SOI) technology. In particular, a semiconductor layer in an SOI platform may include a photonic crystal having a group velocity of light that is less than that of the semiconductor layer. Moreover, an optical modulator (such as a Mach-Zehnder interferometer) may be implemented in the photonic crystal with a vertical junction in the semiconductor layer. During operation of the optical modulator, an input optical signal may be split into two different optical signals that feed two optical waveguides, and then subsequently combined into an output optical signal. Furthermore, during operation, time-varying bias voltages may be applied across the vertical junction in the optical modulator using contacts defined along a lateral direction of the optical modulator.

Abstract: A photonic integrated circuit (PIC) is described. This PIC includes a semiconductor-barrier layer-semiconductor diode in an optical waveguide that conveys an optical signal, where the barrier layer is an oxide or a high-k material. Moreover, semiconductor layers in the semiconductor-barrier layer-semiconductor diode may include geometric features (such as a periodic pattern of holes or trenches) that create a lattice-shifted photonic crystal optical waveguide having a group velocity of light that is lower than the group velocity of light in the first semiconductor layer and the second semiconductor layer without the geometric features. The optical waveguide is included in an optical modulator, such as a Mach-Zehnder interferometer (MZI).

Abstract: A photonic integrated circuit (PIC) is described. This PIC includes a grating coupler for surface-normal coupling that has an alternating pattern of grating teeth and grating trenches, where the grating trenches are filled with an electro-optical material. By applying an electric potential to the grating teeth, the index of refraction of the electro-optical material can be modified.

Abstract: A multi-chip module (MCM) is described. This MCM includes two substrates that are passively self-assembled on another substrate using hydrophilic and hydrophobic materials on facing surfaces of the substrates and liquid surface tension as the restoring force. In particular, regions with a hydrophilic material on the two substrates overlap regions with the hydrophilic material on the other substrate. These regions on the other substrate may be surrounded by a region with a hydrophobic material. In addition, spacers on a surface of at least one of the two substrates may align optical waveguides disposed on the two substrates, so that the optical waveguides are coplanar. This fabrication technique may allow low-loss hybrid optical sources to be fabricated by edge coupling the two substrates. For example, a first of the two substrates may be a III/V compound semiconductor and a second of the two substrates may be a silicon-on-insulator photonic chip.

Abstract: A fabrication technique for cleaving a substrate in an integrated circuit is described. During this fabrication technique, a trench is defined on a back side of a substrate. For example, the trench may be defined using photoresist and/or a mask pattern on the back side of the substrate. The trench may extend from the back side to a depth less than a thickness of the substrate. Moreover, a buried-oxide layer and a semiconductor layer may be disposed on a front side of the substrate. In particular, the substrate may be included in a silicon-on-insulator technology. By applying a force proximate to the trench, the substrate may be cleaved to define a surface, such as an optical facet. This surface may have high optical quality and may extend across the substrate, the buried-oxide layer and the semiconductor layer.

Abstract: A fabrication technique for cleaving a substrate in an integrated circuit is described. During this fabrication technique, a trench is defined on a back side of a substrate. For example, the trench may be defined using photoresist and/or a mask pattern on the back side of the substrate. The trench may extend from the back side to a depth less than a thickness of the substrate. Moreover, a buried-oxide layer and a semiconductor layer may be disposed on a front side of the substrate. In particular, the substrate may be included in a silicon-on-insulator technology. By applying a force proximate to the trench, the substrate may be cleaved to define a surface, such as an optical facet. This surface may have high optical quality and may extend across the substrate, the buried-oxide layer and the semiconductor layer.

Abstract: A multi-chip module (MCM) is described. This MCM includes two substrates that are passively self-assembled on another substrate using hydrophilic and hydrophobic materials on facing surfaces of the substrates and liquid surface tension as the restoring force. In particular, regions with a hydrophilic material on the two substrates overlap regions with the hydrophilic material on the other substrate. These regions on the other substrate may be surrounded by a region with a hydrophobic material. In addition, spacers on a surface of at least one of the two substrates may align optical waveguides disposed on the two substrates, so that the optical waveguides are coplanar. This fabrication technique may allow low-loss hybrid optical sources to be fabricated by edge coupling the two substrates. For example, a first of the two substrates may be a III/V compound semiconductor and a second of the two substrates may be a silicon-on-insulator photonic chip.

Abstract: An optical device is described. This optical device includes optical components having resonance wavelengths that match target values with a predefined accuracy (such as 0.1 nm) and with a predefined time stability (such as permanent or an infinite time stability) without thermal tuning and/or electronic tuning. The stable, accurate resonance wavelengths may be achieved using a wafer-scale, single (sub-second) shot trimming technique that permanently corrects the phase errors induced by material variations and fabrication inaccuracies in the optical components (and, more generally, resonant silicon-photonic optical components). In particular, the trimming technique may use photolithographic exposure of the optical components on the wafer in parallel, with time-modulation for each individual optical component based on active-element control.

Abstract: An integrated circuit includes an optical source (such as a laser) with a lens, which is disposed on an isolator. This isolator is disposed on a semiconductor layer in a silicon-on-insulator (SOI) platform that includes an optical coupler and an optical waveguide. During operation, the optical source generates an optical signal that propagates toward the isolator so that the lens focuses the optical signal. Furthermore, the isolator reduces or eliminates back reflection of the optical signal toward the optical source, and the optical coupler couples the optical signal into the optical waveguide.

Abstract: When an unsafe port with a loss of signal is detected, a transceiver may enable one laser in a group of lasers associated with the unsafe port and may disable the remaining lasers. Then, the transceiver may instruct a transmitter associated with the one laser to transmit an optical signal on the unsafe port using a reduced transmit power that is less than a threshold value associated with the Class 1 conditions and at a different time than enabled lasers in other groups of lasers. Alternatively, for a safe port on which valid communication is received, the transceiver may enable lasers in a group of lasers associated with the safe port. Then, the transceiver may instruct transmitters associated with the lasers in this group of lasers to transmit optical signals on the safe port using a normal transmit power for the lasers that is greater than the threshold value.

Abstract: An optical device includes an optical reflector based on a coupled-loopback optical waveguide. In particular, an input port, an output port and an optical loop in arms of the optical reflector are optically coupled to a directional coupler. The directional coupler evanescently couples an optical signal between the arms. For example, the directional coupler may include: a multimode interference coupler and/or a Mach-Zehnder Interferometer (MZI). Moreover, destructive interference during the evanescent coupling determines the reflection and transmission power coefficients of the optical reflector.

Abstract: An integrated circuit is described. This integrated circuit includes a ferroelectric layer disposed on top of the ring resonator, which has a resonance wavelength. The ferroelectric layer is positioned between electrical contacts. Moreover, there may be amorphous semiconductor materials between the electrical contacts and the ferroelectric layer. For example, the amorphous semiconductor materials may include: p-type amorphous silicon and/or n-type amorphous silicon. By applying a reverse-bias voltage across the electrical contacts, an electric field is generated in a plane approximately parallel to a top surface of the ring resonator. This electric field electro-optically tunes the resonance wavelength. The ring resonator may operate at low voltage and can be integrated with a silicon optical waveguide on a silicon-on-insulator (SOI) platform.

Abstract: An optical device includes an optical reflector based on a coupled-loopback optical waveguide. In particular, an input port, an output port and an optical loop in arms of the optical reflector are optically coupled to a directional coupler. The directional coupler evanescently couples an optical signal between the arms. For example, the directional coupler may include: a multimode interference coupler and/or a Mach-Zehnder Interferometer (MZI). Moreover, destructive interference during the evanescent coupling determines the reflection and transmission power coefficients of the optical reflector.

Abstract: An optical device is described. This optical device includes optical components having resonance wavelengths that match target values with a predefined accuracy (such as 0.1 nm) and with a predefined time stability (such as permanent or an infinite time stability) without thermal tuning and/or electronic tuning. The stable, accurate resonance wavelengths may be achieved using a wafer-scale, single (sub-second) shot trimming technique that permanently corrects the phase errors induced by material variations and fabrication inaccuracies in the optical components (and, more generally, resonant silicon-photonic optical components). In particular, the trimming technique may use photolithographic exposure of the optical components on the wafer in parallel, with time-modulation for each individual optical component based on active-element control.

Abstract: An integrated optical device includes an electro-absorption modulator disposed on a top surface of an optical waveguide. The electro-absorption modulator includes germanium disposed in a cavity between an n-type doped silicon sidewall and a p-type doped silicon sidewall. By applying a voltage between the n-type doped silicon sidewall and the p-type doped silicon sidewall, an electric field can be generated in a plane of the optical waveguide, but perpendicular to a propagation direction of the optical signal. This electric field shifts a band gap of the germanium, thereby modulating the optical signal.

Abstract: A chip package includes an optical integrated circuit (such as a hybrid integrated circuit) and an integrated circuit that are proximate to each other in the chip package. The integrated circuit includes electrical circuits that modulate data, communicate data, and serialize/deserialize data, and the optical integrated circuit communicates optical signals with very high bandwidth. Moreover, a front surface of the integrated circuit is electrically coupled to a top surface of an interposer, and a top surface of the integrated circuit is electrically coupled to a front surface of the optical integrated circuit. Furthermore, a bottom surface of the optical integrated circuit faces the top surface of the interposer, and the front surface of the optical integrated circuit is optically coupled to an optical-fiber receptacle, which in turn is optically coupled to an optical-fiber connector.

Abstract: An optical source is described. This optical source includes a semiconductor optical amplifier, with a semiconductor other than silicon, which provides a gain medium. In addition, a photonic chip, optically coupled to the semiconductor optical amplifier, includes: an optical waveguide that conveys the optical signal; and a pair of ring-resonator modulators that modulate the optical signal. Furthermore, the pair of ring-resonator modulators is included within an optical cavity in the optical source. For example, the optical cavity may be defined by a reflective coating on one edge of the semiconductor optical amplifier and a reflector on one end of the optical waveguide. Alternatively, the optical cavity may be defined by reflectors on ends of the optical waveguide.