Abstract: An optical device is described. This optical device includes multiple components, such as a ring resonator, an optical waveguide and a grating coupler, having a common etch depth (which is associated with a single etch step or operation during fabrication). Moreover, these components may be implemented in a semiconductor layer in a silicon-on-insulator technology. By using a common etch depth, the optical device may provide: compact active devices, multimode ultralow-loss optical waveguides, high-speed ring resonator modulators with ultralow power consumption, and compact low-loss interlayer couplers for multilayer-routed optical links. Furthermore, the single etch step may help reduce or eliminate optical transition loss, and thus may facilitate high yield and low manufacturing costs.

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 MCM may include a single optical routing layer that provides point-to-point connectivity among N chips in the MCM, such as all-to-all connectivity or full-mesh point-to-point connectivity. Moreover, the optical routing layer may include: N optical waveguides optically coupled to the N chips and a cyclic de-multiplexer, optically coupled to the N optical waveguides, that routes optical signals among the N optical waveguides without optical-waveguide crossing in the optical routing layer. For example, the cyclic de-multiplexer may include: an array-waveguide-grating (AWG) wavelength router and/or an echelle-grating wavelength router.

Abstract: In an optical device, a ring resonator, having a resonance wavelength, optically couples an optical signal that includes a wavelength from an input optical waveguide to an output optical waveguide. A monitoring mechanism in the optical device, which is optically coupled to the output optical waveguide, monitors an output optical signal on the output optical waveguide. For example, the monitoring mechanism may dither a temperature of the ring resonator at a frequency using a heater, and the output optical signal may be monitored by determining amplitude and phase information of the output optical signal at the frequency and twice the frequency. Moreover, control logic in the optical device adjusts the resonance wavelength based on the monitored output optical signal, where the adjustment is made without monitoring an input optical signal on the input optical waveguide.

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, such as memory or a processor, 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 this top surface is in turn electrically coupled to a front surface of an input/output (I/O) integrated circuit that faces the top surface. Furthermore, the front surface of the I/O integrated circuit is electrically coupled to a top surface of the optical integrated circuit, where the top surface of the optical integrated circuit faces the front surface of the I/O integrated circuit.

Abstract: Using silicon photonic components that support a single polarization, the output of an optical receiver is independent of the polarization of an optical signal. In particular, using a polarization-diversity technique, the two orthogonal polarizations in a single-mode optical fiber are split in two and processed independently. For example, the two optical signals are provided by a polarizing splitting grating coupler. Subsequently, a wavelength channel in the two optical signals is selected using a wavelength-selective filter (for example, using a ring resonator or an echelle grating) and combined at an optical detector (such as a photo-detector) to achieve polarization-independent operation.

Abstract: In a multiple-wavelength laser source, a multiple-mode laser outputs a set of wavelengths in a range of wavelengths onto an optical waveguide, where a spacing between adjacent wavelengths in the set of wavelengths is smaller than a width of channels in an optical link. Furthermore, a set of ring-resonator filters in the multiple-wavelength laser source, which are optically coupled to the optical waveguide, output corresponding subsets of the set of wavelengths for use in the optical link based on free spectral ranges and quality factors of the set of ring-resonator filters. These subsets may include one or more groups of wavelengths, with another spacing between adjacent groups of wavelengths that is larger than the width of the given channel in the optical link. In addition, the one or more groups of wavelengths may include one or more wavelengths, with the spacing between adjacent wavelengths in the given group of wavelengths.

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: A hybrid optical source that provides an optical signal having a wavelength is described. This hybrid optical source comprises an optical amplifier (such as a III-V semiconductor optical amplifier) that is butt-coupled or vertically coupled to a silicon-on-insulator (SOI) platform, and which outputs an optical signal. The SOI platform comprises an optical waveguide that conveys the optical signal. A temperature-compensation element included in the optical waveguide compensates for temperature dependence of the indexes of refraction of the optical amplifier and the optical waveguide. In addition, a reflector, included in or in-line with the optical waveguide and after the temperature-compensation element, reflects a portion of the optical signal and transmits another portion of the optical signal that has the wavelength.

Abstract: A chip package includes an optical integrated circuit (such as a hybrid integrated circuit) and an integrated circuit that are adjacent to each in the chip package. The integrated circuit includes electrical circuits, such as memory or a processor, 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 front surface of the optical integrated circuit by a top surface of the interposer, where the top surface faces the front surface of the integrated circuit and the front surface of the optical integrated circuit. Furthermore, the integrated circuit and the optical integrated circuit may be on a same side of the interposer. By integrating the optical integrated circuit and the integrated circuit in close proximity, the chip package may facilitate improved performance compared to chip packages with electrical interconnects.

Abstract: A system includes optical modules. Each module includes a different base and one or more module waveguides on the base. Module waveguides from different modules are aligned such that the aligned module waveguides exchange light signals. At least a portion of one of the aligned module waveguides is between the base of one of the modules and the base of another module. First electronics operate a transmitter on a first one of the optical modules so as to generate one of the light signals. Second electronics operate a receiver on a second one of the modules such that the electronics generate an electrical signal in response to the receiver receiving one of the light signals.

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 photonic integrated circuit (PIC) is described. This PIC includes an inverse facet mirror on a silicon optical waveguide for optical proximity coupling between two silicon-on-insulator (SOI) chips placed face to face. Accurate mirror facets may be fabricated in etch pits using a silicon micro-machining technique, with wet etching of the silicon <110> facet at an angle of 45° when etched through the <100> surface. Moreover, by filling the etch pit with polycrystalline silicon or another filling material that has an index of refraction similar to silicon (such as a silicon-germanium alloy), a reflecting mirror with an accurate angle can be formed at the end of the silicon optical waveguide using: a metal coating, a dielectric coating, thermal oxidation, or selective silicon dry etching removal of one side of the etch pit to define a cavity.

Abstract: A photonic integrated circuit (PIC) that includes an optical source that provides an optical signal having a wavelength is described. This optical source includes a reflecting layer, a bottom cladding layer, an active layer (such as a III-V semiconductor) having a bandgap wavelength that exceeds that of silicon, and a top cladding layer. Moreover, an optical coupler (such as a grating coupler) that couples the optical signal out of a plane of the active layer is included in a region of the active layer. In this region, the top cladding layer is absent. Furthermore, in an adjacent region, the top cladding layer includes an inverse taper so that the top cladding layer is tapered down from a width distal from the region. In conjunction with the optical coupler, the inverse taper may facilitate low-loss optical coupling of the optical signal between the PIC and another PIC.

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 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: In an optical device, a ring resonator, having a resonance wavelength, optically couples an optical signal that includes a wavelength from an input optical waveguide to an output optical waveguide. A monitoring mechanism in the optical device, which is optically coupled to the output optical waveguide, monitors an output optical signal on the output optical waveguide. For example, the monitoring mechanism may dither a temperature of the ring resonator at a frequency using a heater, and the output optical signal may be monitored by determining amplitude and phase information of the output optical signal at the frequency and twice the frequency. Moreover, control logic in the optical device adjusts the resonance wavelength based on the monitored output optical signal, where the adjustment is made without monitoring an input optical signal on the input optical waveguide.

Abstract: A hybrid optical source includes a substrate with an optical amplifier (such as a III-V semiconductor optical amplifier). The substrate is coupled at an angle (such as an angle between 0 and 90°) to a silicon-on-insulator chip. In particular, the substrate may be optically coupled to the silicon-on-insulator chip by an optical coupler (such as a diffraction grating or a mirror) that efficiently couples (i.e., with low optical loss) an optical signal into a sub-micron silicon-on-insulator optical waveguide. Moreover, the silicon-on-insulator optical waveguide optically couples the light to a reflector to complete the hybrid optical source.

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 photonic integrated circuit (PIC) that includes an optical source that provides an optical signal having a wavelength is described. This optical source includes a reflecting layer, a bottom cladding layer, an active layer (such as a III-V semiconductor) having a bandgap wavelength that exceeds that of silicon, and a top cladding layer. Moreover, an optical coupler (such as a grating coupler) that couples the optical signal out of a plane of the active layer is included in a region of the active layer. In this region, the top cladding layer is absent. Furthermore, in an adjacent region, the top cladding layer includes an inverse taper so that the top cladding layer is tapered down from a width distal from the region. In conjunction with the optical coupler, the inverse taper may facilitate low-loss optical coupling of the optical signal between the PIC and another PIC.