Leland Stanford Junior University

University of California

Powx Inc.

Wayne H. Knox

David A. B. Miller

David A B Miller

James S Harris, Jr

Yu-Hsuan Kuo

Vijit Sabnis

Helen L Kung

Krishna Coimbatore Balram

Martina Gerken

Shanhui Fan

Olav Solgaard

Pawan Kapur

Sung-Joo Ben Yoo

Michael Dubrovsky

Hilmi Volkan Demir

Michael West Wiemer

Stephanie Claussen

Bianca E Nelson

Shen Ren

Sunil K Pai

Bogdan Penkovsky

Maynard Marshall Ball, Jr

Jonathan E Roth

Hilml Volkan Demir

Ray Chen

Wayne H Knox

An apparatus for combined digital and optical processing of a cryptocurrency data block includes a digital processor that computes a hash vector from the cryptocurrency data block; a laser and splitter that produces optical input signals; optical modulators that binary phase-shift key modulate the optical input signals based on the hash vector; a photonic matrix multiplier circuit that performs an optically perform a discrete matrix-vector product operation on the modulated optical input signals to produce optical output signals, where the discrete matrix-vector product operation is defined by matrix elements limited to K discrete values, where 2≤K≤17; and photodetectors and comparators that perform optoelectronic conversions of the optical output signals to produce corresponding digital electronic output signals. The digital processor performs a second hash computation on an XOR result between the digital electronic output signals and the hash vector to produce a proof of work result.

Photonic blockchain based on optical proof-of-work

The disclosed embodiments relate to a system that implements a photonic neuron. This photonic neuron includes: an excitatory-input photo detector that converts an optical excitatory input signal into a corresponding electrical excitatory input signal; and an inhibitory-input photo detector that converts an optical inhibitory input signal into a corresponding electrical inhibitory input signal. It also includes an electrical neuron that receives the electrical excitatory and inhibitory input signals, and generates an electrical output signal, which includes periodic voltage spikes that are triggered by integration of the electrical excitatory and inhibitory input signals. Finally, the photonic neuron includes a light-emitting output device, which converts the electrical output signal into a corresponding optical output signal.

Implementing a neuromorphic computing system using nanophotonic neurons

Universal linear components are provided. In general, a P input and Q output wave combiner is connected to a Q input and R output wave mode synthesizer via Q amplitude and/or phase modulators. The wave combiner and wave mode synthesizer are both linear, reciprocal and lossless. The wave combiner and wave mode synthesizer can be implemented using waveguide technology. This device can provide any desired linear transformation of spatial modes between its inputs and its outputs. This capability can be generalized to any linear transformation by using representation converters to convert other quantities to spatial mode patterns. The wave combiner and wave mode synthesizer are also useful separately, and can enable applications including self-adjusting mode coupling, optimal multi-mode communication, and add-drop capability in a multi-mode system. Control of the wave combiner and wave mode synthesizer can be implemented with single-variable optimizations.

Universal linear components

A modified directional coupler structure is used to provide a controllable time delay or phase shift for radiation propagating through the structure. A longitudinal displacement of the interaction region of the directional coupler relative to one or both of the waveguides of the directional coupler provides this effect. Double flexure arrangements can be used to provide longitudinal displacement with substantially no corresponding lateral displacement (or vice versa). In some embodiments, lateral and longitudinal displacement of the waveguides of the directional coupler are independently adjustable to provide full control of the power splitting and phase shift/time delay of the directional coupler.

Phase shifting by mechanical movement

Methods are known for implementing general optical functions using wave splitters. However, these methods rely on these wave splitters having maximal extinction ratio, which is difficult to achieve in practice. The present invention provides methods for automatically adjusting wave splitters to provide maximal extinction ratio.

Field-programmable optical component

A robust fabrication process for selective area growth of semiconductors in growth windows is provided. Sidewall growth is eliminated by the presence of a spacer layer which covers the sidewalls. Undesirable exposure of the top corners of the growth windows is prevented by undercutting the growth window prior to deposition of the dielectric spacer layer. The effectiveness of this process has been demonstrated by selective-area growth of Ge and Ge/SiGe quantum wells on a silicon substrate. Integration of active optoelectronic devices with waveguide layers via end-coupling through the dielectric spacer layer can be reliably accomplished in this manner.

Selective area growth of germanium and silicon-germanium in silicon waveguides for on-chip optical interconnect applications

A photodetector having a ridge-in-slit geometry is provided, where a semiconductor ridge is laterally sandwiched in a metallic slit. This assembly is disposed on a layer of semiconducting material, which in turn is disposed on an insulating substrate. These structures can provide efficient resonant detectors having the wavelength of peak response set by the ridge width. Thus a lateral feature defines the wavelength of peak responsivity, as opposed to a vertical feature.

Self-aligned semiconductor ridges in metallic slits as a platform for planar tunable nanoscale resonant photodetectors

Improved integration of optoelectronic devices is provided by a spacer layer laterally sandwiched between distinct regions that are monolithically fabricated onto the same substrate (e.g., by selective epitaxy). An optical waveguide in one of the regions can optically couple to an optoelectronic device in another of the regions through the spacer layer, thereby providing a monolithically integrated form of butt-coupling. Preferably, the spacer layer thickness is less than about 50 nm, and is more preferably less than about 20 nm, to reduce optical loss. The spacer layer is preferably electrically insulating, to prevent shorting of devices grown by selective epitaxy.

Integration of optoelectronics with waveguides using interposer layer

Si&#x2014;Ge quantum wells where the well material has a lowest conduction band energy minimum at k=0 (the &#x393; point of the first Brillouin zone) are provided. Quantum well structures that satisfy this condition have 'Kane-like' bands at and near k=0 which can provide physical effects useful for various device applications, especially optical modulators. In the SiGematerial system, this condition on the band structure is satisfied for x greater than about 0.7. The quantum well barrier composition may or may not have Kane-like bands. A preferred method of providing such quantum well structures on a substrate (e.g., a silicon substrate) is to grow a first Ge-rich Si&#x2014;Ge buffer layer on the substrate, and then anneal the resulting layered structure. In many cases it is further preferred to grow a second Ge-rich Si&#x2014;Ge buffer layer on top of the first buffer layer and anneal the resulting layered structure.

Ge-Si quantum well structures

An electro-optic semiconductor device (e.g., an optical modulator) having side access and beam propagation within the device is provided. Side access for the optical input and/or output facilitates disposition of electronic circuitry and/or heat sinking structures on the top and bottom surfaces of the modulator. Internal beam propagation instead of internal waveguiding advantageously simplifies optical coupling and alignment to the modulator. Interaction length within the device is preferably enhanced by passing through the device active region at a relatively shallow angle. The internally propagating beam is reflected from a reflective face parallel to the device active region. The side faces can be perpendicular or tilted with respect to the reflective face. Tilted side faces are preferably tilted to provide external beam paths parallel to the reflective face. Internal reflection from an angled side face can be employed to provide configurations having one side port and one top or bottom port.

Optical modulator with side access

SiGe quantum wells where the well material has a lowest conduction band energy minimum at k=0 (the &#x393; point of the first Brillouin zone) are provided. Quantum well structures that satisfy this condition have 'Kane-like' bands at and near k=0 which can provide physical effects useful for various device applications, especially optical modulators. In the SiGematerial system, this condition on the band structure is satisfied for x greater than about 0.7. The quantum well barrier composition may or may not have Kane-like bands. Optical modulators and/or detectors according to the invention are suitable for inclusion in waveguide-based optical interconnects. Such interconnects can be on-chip interconnects or chip to chip interconnects.

Silicon-based Ge/SiGe optical interconnects

SiGe quantum wells where the well material has a lowest conduction band energy minimum at k=0 (the &#x393; point of the first Brillouin zone) are provided. Quantum well structures that satisfy this condition have 'Kane-like' bands at and near k=0 which can provide physical effects useful for various device applications, especially optical modulators. In the SiGematerial system, this condition on the band structure is satisfied for x greater than about 0.7. The quantum well barrier composition may or may not have Kane-like bands. Optical modulators including such SiGe quantum wells can be operated at temperatures other than room temperature. Such temperature control is preferred for providing optical modulators that operate in the telecommunication C band (&#x2dc;1530 nm to &#x2dc;1565 nm).

Temperature-controlled optical modulator

An optical switch assembly is provided having a plurality of optoelectronic switching nodes. Each node is a three terminal optical device having a first optical input, a second optical input and an optical output. Each node can be electrically activated or deactivated via an electrical control input. Each node has a transmittance between its second optical input and its optical output. This transmittance depends on the signal at the first optical input if the node is activated, and is independent of the first optical input if the node is deactivated. Thus modulation at the first optical input can be selectively imposed on the optical output. The switch includes at least two chains of nodes, each chain having two or more nodes connected in series such that each pair of adjacent nodes is connected from optical output to second optical input. Switches according to the invention can be configured as optical crossbar switches or optical routers.

Optoelectronic switch having cascaded optical nodes

SiGe quantum wells where the well material has a lowest conduction band energy minimum at k=0 (the &#x393; point of the first Brillouin zone) are provided. Quantum well structures that satisfy this condition have 'Kane-like' bands at and near k=0 which can provide physical effects useful for various device applications, especially optical modulators. In the SiGematerial system, this condition on the band structure is satisfied for x greater than about 0.7. The quantum well barrier composition may or may not have Kane-like bands. Embodiments of the invention having a surface parallel configuration are especially suitable for use in fiber coupled devices. Such surface parallel devices have light propagating in the plane of the quantum wells, in a device geometry that is preferably not single-mode waveguided.

Growing community of inventors

Stanford, CA, United States of America

David A B Miller