Abstract: A MOSCAP phase adjuster includes two conductive regions with a thin insulating region therebetween, where charge is accumulated or depleted. In conventional MOSCAP modulators, the conductive and insulating regions are superposed layers, extending horizontally parallel to the substrate, which limits waveguide design and mode confinement, resulting in reduced phase shift performance. An improved MOSCAP phase adjuster and method of fabricating a MOSCAP phase adjuster includes depositing the material for the second conductive region beside and over top of the first conductive region after oxidation, and selectively etching the material to form the second conductive region.

Abstract: A SOI bent taper structure is used as a mode convertor. By tuning the widths of the bent taper and the bend angles, almost lossless mode conversion is realized between TE0 and TE1 in a silicon waveguide. The simulated loss is <0.05 dB across C-band. This bent taper can be combined with bi-layer TM0-TE1 rotator to reach very high efficient TM0-TE0 polarization rotator. An ultra-compact (9 ?m) bi-layer TM0-TE1 taper based on particle swarm optimization is demonstrated. The entire TM0-TE0 rotator has a loss <0.25 dB and polarization extinction ratio >25 dB, worst-case across the C-band.

Abstract: A low loss high extinction ratio on-chip polarizer is disclosed. The polarizer is formed of a mode convertor followed by a mode squeezer and a dump waveguide, and may be configured to pass a desired waveguide mode and reject undesired modes. An embodiment is described that transmits a TE0 mode while blocking a TM0 mode by converting it into a higher-order TEn mode in a waveguide taper, squeezing out the TEn mode in a second waveguide taper to lessen its confinement, and then dumping the TEn mode in a waveguide bend that is configured to pass the TE0 mode.

Abstract: A MOSCAP phase adjuster includes two conductive regions with a thin insulating region therebetween, where charge is accumulated or depleted. In conventional MOSCAP modulators, the conductive and insulating regions are superposed layers, extending horizontally parallel to the substrate, which limits waveguide design and mode confinement, resulting in reduced phase shift performance. An improved MOSCAP phase adjuster and method of fabricating a MOSCAP phase adjuster includes depositing the material for the second conductive region beside and over top of the first conductive region after oxidation, and selectively etching the material to form the second conductive region.

Abstract: An optical circuit capable of operating as a 90° optical hybrid includes a phase-symmetric optical splitter and a 90° optical splitter, and two 2×2 optical couplers as optical combiners. The input ports of the optical combiners and the output ports of the optical splitters face a common area therebetween, with the optical splitters interposed between optical combiners as viewed along the circumference of the common area. The output ports of each optical splitter is connected to closest input ports of the optical combiners with optical waveguides of a same length. The length of the waveguides may be minimized when the optical couplers and the optical splitters are disposed in a cross-like configuration.

Abstract: A SOI bent taper structure is used as a mode convertor. By tuning the widths of the bent taper and the bend angles, almost lossless mode conversion is realized between TE0 and TE1 in a silicon waveguide. The simulated loss is <0.05 dB across C-band. This bent taper can be combined with bi-layer TM0-TE1 rotator to reach very high efficient TM0-TE0 polarization rotator. An ultra-compact (9 ?m) bi-layer TM0-TE1 taper based on particle swarm optimization is demonstrated. The entire TM0-TE0 rotator has a loss <0.25 dB and polarization extinction ratio >25 dB, worst-case across the C-band.

Abstract: Practical silicon-based light sources are still missing, despite the progress in germanium lasers, because both silicon and germanium are indirect-band semiconductors and inefficient at light generation. A tunable and single mode external cavity laser comprising: a gain medium for generating light between a reflective surface at one end of the gain medium; and a wavelength selective reflector at the other end of a laser cavity. A splitter disposed in the laser cavity includes an input port optically coupled to the gain medium, an input/output port optically coupled to the wavelength selective reflector, and an output port for outputting laser light at selected wavelengths. The wavelength selective reflector reflects light of one or more selected periodic wavelengths back to the gain medium via the input/output port, and passes light of non-selected wavelengths out of the laser cavity.

Abstract: A low loss high extinction ratio on-chip polarizer is disclosed. The polarizer includes an input waveguide taper having an outer waveguiding region that widens in the direction of light propagation along at least a portion of the taper length, and a core waveguiding region that narrows in the direction of light propagation along at least a portion of the taper length, so as to selectively squeeze out light of undesired modes into the outer regions while preserving light of a desired mode in the waveguide core. An output filter section is provided to prevent light from reentering the output waveguide after being squeezed out. An integrated light absorber/deflector may be coupled to the outer waveguiding regions.

Abstract: A low loss high extinction ratio on-chip polarizer is disclosed. The polarizer is formed of a mode convertor followed by a mode squeezer and a dump waveguide, and may be configured to pass a desired waveguide mode and reject undesired modes. An embodiment is described that transmits a TE0 mode while blocking a TM0 mode by converting it into a higher-order TEn mode in a waveguide taper, squeezing out the TEn mode in a second waveguide taper to lessen its confinement, and then dumping the TEn mode in a waveguide bend that is configured to pass the TE0 mode.

Abstract: A dual-differential optical modulator includes two optical waveguide arms, each including one or more phase modulating p/n junctions. The p/n junctions in each waveguide arm are electrically coupled between a same pair of single-ended transmission lines so as to be differentially push-pull modulated when the transmission line pair is connected to a differential driver. Either cathode or anode electrodes of the p/n junctions are AC coupled to the transmission lines and DC biased independently on the transmission line signals.

Abstract: A compact, low-loss and wavelength insensitive Y-junction for submicron silicon waveguides. The design was performed using FDTD and particle swarm optimization (PSO). The device was fabricated in a 248 nm CMOS line. Measured average insertion loss is 0.28±0.02 dB across an 8-inch wafer. The device footprint is less than 1.2 ?m×2 ?m, orders of magnitude smaller than MMI and directional couplers.

Abstract: Practical silicon-based light sources are still missing, despite the progress in germanium lasers, because both silicon and germanium are indirect-band semiconductors and inefficient at light generation. A tunable and single mode external cavity laser comprising: a gain medium for generating light between a reflective surface at one end of the gain medium; and a wavelength selective reflector at the other end of a laser cavity. A splitter disposed in the laser cavity includes an input port optically coupled to the gain medium, an input/output port optically coupled to the wavelength selective reflector, and an output port for outputting laser light at selected wavelengths. The wavelength selective reflector reflects light of one or more selected periodic wavelengths back to the gain medium via the input/output port, and passes light of non-selected wavelengths out of the laser cavity.

Abstract: An integrated polarization splitter and rotator (PSR) employs the TE0 and TE1 modes of propagating light, rather than the TE0 and TM0 modes used in conventional prior art PSR. The integrated PSR exhibits appreciably flatter wavelength response because it does not require a directional coupler to de-multiplex incoming polarizations. The PSR allows tuning of the TM0 loss to reduce polarization dependent loss (PDL). This integrated polarization splitter and rotator is applicable to all integrated platforms including Silicon-on-Insulator (SOI) and III-V semiconductor compound systems. The PSR may be very compact (12×2 ?m2), and provides low loss (<0.3 dB across the C-band) and ultra-broadband operation. The PSR also affords better control of polarization dependent losses.

Abstract: An optical circuit capable of operating as a 90° optical hybrid includes a phase-symmetric optical splitter and a 90° optical splitter, and two 2×2 optical couplers as optical combiners. The input ports of the optical combiners and the output ports of the optical splitters face a common area therebetween, with the optical splitters interposed between optical combiners as viewed along the circumference of the common area. The output ports of each optical splitter is connected to closest input ports of the optical combiners with optical waveguides of a same length. The length of the waveguides may be minimized when the optical couplers and the optical splitters are disposed in a cross-like configuration.

Abstract: A multimode interference (MMI) coupler with an MMI region of curved edges, and a method of design and manufacturing by using a computerized optimization algorithm to determine a favorable set of segment widths for the MMI region for a predefined set of coupler design parameters.

Abstract: A low loss high extinction ratio on-chip polarizer. The polarizer includes an input waveguide taper having an outer waveguiding region that widens in the direction of light propagation along at least a portion of the taper length, and a core waveguiding region that narrows in the direction of light propagation along at least a portion of the taper length, so as to selectively squeeze out light of undesired modes into the outer regions while preserving light of a desired mode in the waveguide core. An output filter section is provided to prevent light from reentering the output waveguide after being squeezed out. An integrated light absorber/deflector may be coupled to the outer waveguiding regions.

Abstract: A dual-differential optical modulator includes two optical waveguide arms, each including one or more phase modulating p/n junctions. The p/n junctions in each waveguide arm are electrically coupled between a same pair of single-ended transmission lines so as to be differentially push-pull modulated when the transmission line pair is connected to a differential driver. Either cathode or anode electrodes of the p/n junctions are AC coupled to the transmission lines and DC biased independently on the transmission line signals.

Abstract: A dual-differential optical modulator includes two optical waveguide arms, each including one or more phase modulating p/n junctions. The p/n junctions in each waveguide arm are electrically coupled between a same pair of single-ended transmission lines so as to be differentially push-pull modulated when the transmission line pair is connected to a differential driver. Either cathode or anode electrodes of the p/n junctions are AC coupled to the transmission lines and DC biased independently on the transmission line signals.

Abstract: An integrated polarization splitter and rotator (PSR) employs the TE0 and TE1 modes of propagating light, rather than the TE0 and TM0 modes used in conventional prior art PSR. The integrated PSR exhibits appreciably flatter wavelength response because it does not require a directional coupler to de-multiplex incoming polarizations. The PSR allows tuning of the TM0 loss to reduce polarization dependent loss (PDL). This integrated polarization splitter and rotator is applicable to all integrated platforms including Silicon-on-Insulator (SOI) and III-V semiconductor compound systems. The PSR may be very compact (12×2 ?m2), and provides low loss (<0.3 dB across the C-band) and ultra-broadband operation. The PSR also affords better control of polarization dependent losses.

Abstract: A light shield may be formed in photonic integrated circuit between integrated optical devices of the photonic integrated circuit. The light shield may be built by using materials already present in the photonic integrated circuit, for example the light shield may include metal walls and doped semiconductor regions. Light-emitting or light-sensitive integrated optical devices or modules of a photonic integrated circuit may be constructed with light shields integrally built in.