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: An optical modulator apparatus may include a plurality of segment drivers, each segment driver having a unique offset voltage and driving but a portion or a segment of an electro-optical modulator. A modulating electrical signal may be applied to the segment drivers via a plurality of electrical delays. Parameters of the segment drivers may be selected so as to approximate a pre-defined transfer function, which may include a linear or a non-linear transfer function.

Abstract: A test system for determining a surface characteristic of a chip facet comprises a chip, which has a facet and includes a waveguide, a detector, and a processor. The on-chip waveguide is configured to direct test light towards the facet, where a portion of the test light is reflected and a portion of the test light is transmitted. The detector is configured to measure an amount of the reflected portion or the transmitted portion, and the processor is configured to determine a surface characteristic of the facet, such as a facet angle, a facet curvature, and/or a facet roughness, on the basis of the measured amount.

Abstract: In Mach-Zehnder interferometer (MZI) based modulators (MZM) input laser light comes in from one side, gets split into two MZI arms, then recombined at an opposite side. Each MZI arm may be phase or intensity modulated depending on the set phase offset, whereby coherent or intensity modulation may be performed which can later be de-coded by a receiver. Ring resonator type modulators (RRM) are compact; however, their phase response is nonlinear, normally limiting their application in coherent phase modulation. However, a combined MZI RRM overcomes the shortcomings of the prior art by providing a novel structure and driving scheme for use with semiconductor photonics that takes advantage of the compactness of ring modulators and the linearity of MZI by setting the ring resonators to resonate at the input laser light wavelength.

Abstract: A photonic interface for an electronic circuit is disclosed. The photonic interface includes a photonic integrated circuit having a modulator and a photodetector, and an optical fiber or fibers for optical communication with another optical circuit. A modulator driver chip may be mounted directly on the photonic integrated circuit. The optical fibers may be placed in v-grooves of a fiber support, which may include at least one lithographically defined alignment feature for optical alignment to the silicon photonic circuit.

Abstract: A distributed traveling-wave Mach-Zehnder modulator driver having a plurality of modulation stages that operate cooperatively (in-phase) to provide a signal suitable for use in a 100 Gb/s optical fiber transmitter at power levels that are compatible with conventional semiconductor devices and conventional semiconductor processing is described.

Abstract: Two semiconductor chips are optically aligned to form a hybrid semiconductor device. Both chips have optical waveguides and alignment surface positioned at precisely-defined complementary vertical offsets from optical axes of the corresponding waveguides, so that the waveguides are vertically aligned when one of the chips is placed atop the other with their alignment surface abutting each other. The position of the at least one of the alignment surface in a layer stack of its chip is precisely defined by epitaxy. The chips are bonded at offset bonding pads with the alignment surfaces abutting in the absence of bonding material therebetween.

Abstract: A composite optical waveguide is constructed using an array of waveguide cores, in which one core is tapered to a larger dimension, so that all the cores are used as a composite input port, and the one larger core is used as an output port. In addition, transverse couplers can be fabricated in a similar fashion. The waveguide cores are preferably made of SiN. In some cases, a layer of SiN which is provided as an etch stop is used as at least one of the waveguide cores. The waveguide cores can be spaced away from a semiconductor layer so as to minimize loses.

Abstract: Described are various embodiments of a dual optical modulator, system and method. In one embodiment, an optical modulator modulates an input optical signal having a designated optical frequency. The modulator comprises first and second tunable modulators operable around the optical frequency and operatively disposed between a bus waveguide path and an opposed waveguide path. The modulator further comprises a relative optical phase-shifter optically coupled between the tunable modulators so to impart a relative optical phase shift between the bus waveguide path and the opposed waveguide path. The tunable modulators are respectively driveable to modulate a respective resonance thereof in complimentary directions relative to the optical frequency and thereby resonantly redirect a selectable portion of the input optical signal along the opposed waveguide path such that the relative optical phase shift is imparted thereto for output.

Abstract: A Ge-on-Si photodetector constructed without doping or contacting Germanium by metal is described. Despite the simplified fabrication process, the device has responsivity of 1.24 A/W, corresponding to 99.2% quantum efficiency. Dark current is 40 nA at ?4 V reverse bias. 3-dB bandwidth is 30 GHz.

Abstract: An optical modulator apparatus may include a plurality of segment drivers, each segment driver having a unique offset voltage and driving but a portion or a segment of an electro-optical modulator. A modulating electrical signal may be applied to the segment drivers via a plurality of electrical delays. Parameters of the segment drivers may be selected so as to approximate a pre-defined transfer function, which may include a linear or a non-linear transfer function.

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 test system for determining a surface characteristic of a chip facet comprises a chip, which has a facet and includes a waveguide, a detector, and a processor. The on-chip waveguide is configured to direct test light towards the facet, where a portion of the test light is reflected and a portion of the test light is transmitted. The detector is configured to measure an amount of the reflected portion or the transmitted portion, and the processor is configured to determine a surface characteristic of the facet, such as a facet angle, a facet curvature, and/or a facet roughness, on the basis of the measured amount.

Abstract: A high data rate, high sensitivity, low power optical link using low-bandwidth components and low-bandwidth E/O drivers and receivers and method of building same. The method is based on the idea of making the optical part of the link look like a bandwidth limited lossy electrical channel, so that the powerful equalization methods used in the wireline electrical links can be applied to recover the transmitted data in a situation with low bandwidth and/or high loss and strong inter-symbol interference. Linear and non-linear optical channel components, E/O drivers and receivers can benefit from the apparatus and the methods of the invention.

Abstract: A photonic chip includes a device layer and a port layer, with an optical port located at the port layer. Inter-layer optical couplers are provided for coupling light between the device and port layers. The inter-layer couplers may be configured to couple signal light but block pump light or other undesired wavelength from entering the device layer, operating as an input filter. The port layer may accommodate other light pre-processing functions, such as optical power splitting, that are undesirable in the device layer.

Abstract: A photonic interface for an electronic circuit is disclosed. The photonic interface includes a photonic integrated circuit having a modulator and a photodetector, and an optical fiber or fibers for optical communication with another optical circuit. A modulator driver chip may be mounted directly on the photonic integrated circuit. The optical fibers may be placed in v-grooves of a fiber support, which may include at least one lithographically defined alignment feature for optical alignment to the silicon photonic circuit.

Abstract: Described are various embodiments of a dual optical modulator, system and method. In one embodiment, an optical modulator modulates an input optical signal having a designated optical frequency. The modulator comprises first and second tunable modulators operable around the optical frequency and operatively disposed between a bus waveguide path and an opposed waveguide path. The modulator further comprises a relative optical phase-shifter optically coupled between the tunable modulators so to impart a relative optical phase shift between the bus waveguide path and the opposed waveguide path. The tunable modulators are respectively driveable to modulate a respective resonance thereof in complimentary directions relative to the optical frequency and thereby resonantly redirect a selectable portion of the input optical signal along the opposed waveguide path such that the relative optical phase shift is imparted thereto for output.

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 method for on-wafer testing of optical structures of photonic chips that include edge couplers as input/out ports includes defining, in test a test area of the wafer, an edge coupler pair formed of two edge couplers separated by a test gap, which may have a width that is close to the width of a chip-fiber gap during normal operation of the photonic chips. Test areas may include chains of different numbers of the edge coupler pairs for determining coupling loss per edge coupler.

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.