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 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 hybrid optical source that provides an optical signal having a wavelength is described. This hybrid optical source includes an edge-coupled optical amplifier (such as a III-V semiconductor optical amplifier) aligned to a semiconductor reflector (such as an etched silicon mirror). The semiconductor reflector efficiently couples (i.e., with low optical loss) light out of the optical amplifier in a direction approximately perpendicular to a plane of the optical amplifier. A corresponding optical coupler (such as a diffraction grating or a mirror) fabricated on a silicon-on-insulator chip efficiently couples the light into a sub-micron silicon-on-insulator optical waveguide. The silicon-on-insulator optical waveguide couples the light to additional photonic elements (including a reflector) to complete the hybrid optical source.

Abstract: An integrated optical source is described. This optical source outputs one or more optical signals that provide a comb of wavelengths for use in wavelength-division-multiplexing (WDM) optical interconnects or links. In particular, a shared echelle grating is used as a wavelength-selective filter or control device for multiple lasing cavities to achieve self-registered and accurate lasing-channel spacing without inter-channel gain competition. Furthermore, the optical source can be used to provide all the wavelength channels in one optical waveguide or in separate optical waveguides. Therefore, the optical source may be used with cascaded ring-resonator modulators and/or electro-absorption-based broadband modulators.

Abstract: An optical multiplexer/de-multiplexer (MUX/de-MUX) includes a two-dimensional pattern of features in a propagation region that conveys an optical signal having wavelengths. A given feature in this pattern has a characteristic length and the features have an average pitch, both of which are less than fundamental smallest of the wavelengths divided by an effective index of refraction of the propagation region. Moreover, an optical device in the optical MUX/de-MUX images and diffracts the optical signal using a reflective geometry, and provides the imaged and diffracted optical signal to output ports. For example, the optical device may include an echelle grating.

Abstract: An integrated optical device includes a photo-detector (such as germanium) optically coupled to an optical waveguide. This photo-detector is deposited on the optical waveguide, and an optical signal propagating in the optical waveguide may be evanescently coupled to the photo-detector. In order to increase the absorption length of the photo-detector, a mirror (such as a distributed Bragg reflection grating) is included in the optical waveguide near the end of the photo-detector. This mirror reflects the optical signal back toward the photo-detector, thereby increasing the absorption of the optical signal by the photo-detector. In addition, absorption may be reduced by using electrical contacts that are electrically coupled to the photo-detector at locations where the optical mode of the optical signal is largely in the underlying optical waveguide, and by using a fingered metal layer to couple to the electrical contacts.

Abstract: An integrated optical component outputs and receives an optical signal that provides a comb of modulated wavelengths for use in wavelength-division-multiplexing (WDM) optical interconnects or links. In particular, a shared echelle grating is used as a wavelength-selective filter or control device for multiple lasing cavities to achieve self-registered and accurate lasing-channel spacing without inter-channel gain competition for multiplexing modulated wavelength channels into one transmit port, and for receiving and de-multiplexing WDM wavelength channels simultaneously. The wavelength alignment between a pair of such transceivers can be achieved by tuning the echelle grating on one side using thermal-optical or electro-optical effects. Furthermore, tunable ring-resonator modulators, broadband electro-absorption modulators (EAMs) or Mach-Zehnder Interferometer (MZI) optical modulators on the shared output waveguide outside of the lasing cavities can be used to modulate the wavelengths.

Abstract: An integrated optical source is described. This optical source outputs one or more optical signals that provide a comb of wavelengths for use in wavelength-division-multiplexing (WDM) optical interconnects or links. In particular, a shared echelle grating is used as a wavelength-selective filter or control device for multiple lasing cavities to achieve self-registered and accurate lasing-channel spacing without inter-channel gain competition. Furthermore, the optical source can be used to provide all the wavelength channels in one optical waveguide or in separate optical waveguides. Therefore, the optical source may be used with cascaded ring-resonator modulators and/or electro-absorption-based broadband modulators.

Abstract: An optical multiplexer/de-multiplexer (MUX/de-MUX) includes a two-dimensional pattern of features in a propagation region that conveys an optical signal having wavelengths. A given feature in this pattern has a characteristic length and the features have an average pitch, both of which are less than fundamental smallest of the wavelengths divided by an effective index of refraction of the propagation region. Moreover, an optical device in the optical MUX/de-MUX images and diffracts the optical signal using a reflective geometry, and provides the imaged and diffracted optical signal to output ports. For example, the optical device may include an echelle grating.

Abstract: An optical-source monitor images and diffracts received optical signals using an optical device that has a reflective geometry. For example, the optical device may include a diffraction grating on a curved surface, such as an echelle grating. By imaging and diffracting the optical signals, the optical device may couple to the optical signals on different diffraction orders of the optical device (which have different carrier wavelengths) from input optical waveguides to corresponding output optical waveguides. Then, output power monitors may measure the output power levels of the optical signals, and control logic may provide wavelength control signals to optical sources that provide the optical signals based on measured output power levels.

Abstract: An optical de-MUX includes a sub-wavelength grating that magnifies an input optical signal. In particular, along a direction perpendicular to a propagation direction of the optical signal, the sub-wavelength grating has a spatially varying effective index of refraction that is larger at a center of the sub-wavelength grating than at an edge of the sub-wavelength grating. Moreover, the optical de-MUX includes an optical device that images and diffracts the optical signal using a reflective geometry, and which provides different diffraction orders to output ports. For example, the optical device may include an echelle grating.