Washington University

International Business Machines Corporation

Volker J Sorger

Tarek El-Ghazawi

Shuai Sun

Jonathan K George

Vikram K Narayana

Ke Liu

Devendra K Sadana

Ning Li

Mario Miscuglio

Rubab Amin

Armin Mehrabian

Rohit Anil Hemnani

Abdel-Hameed A Badawy

Chandraman Sadanand Patil

Jiaxin Peng

Rishi Maiti

Chenran Ye

Hani Nejadriahi

Zhizhen Ma

Multistate non-volatile photonic memory devices are disclosed. The photonic devices comprise phase change materials with broadband transparencies used to store discretized information with negligible losses in the 0 state. The photonic memories comprise multiple configurations for reading and writing multi-bit words. The reading mechanisms comprises schemes based on light-absorption (FIG.), shift in resonances of a cavity (ring resonator, photonic crystal; FIG.) or interferometric schemes (FIG.). The photonic memory devices employ multiple techniques for writing electrically (FIG.and related performance) and/or all-optically (FIGS.-). The optical writing can be performed with pulsed laser light coming either from free space or on-chip using dedicated writing lines and opportune drops.

Low loss multistate photonic memories

A photonic Mach Zehnder Interferometer (MZI) has a first arm with a first photonic waveguide transmitting a first light having a first phase, a second arm with a second photonic waveguide transmitting a second light having a second phase, and a Transparent Conducting Oxide (TCO) based assembly. The TCO assembly is positioned about the first photonic waveguide of the first arm to modulate the first phase of the first light traveling in the first photonic waveguide.

Transparent conducting oxide (TCO) based integrated modulators

A photonic device that includes two electrodes and a two-dimensional (2D) material electrically connecting the two electrodes. The 2D material may be molybdenum ditelluride. Strain may be induced in the 2D material (e.g., by placing the 2D material on a waveguide) to reduce the band gap of the 2D material and increase the efficiency of the photodetector. The photonic device may be a photodetector with 2D material that absorbs light energy and converts it into a photocurrent in a circuit that includes the two electrodes. The photonic device may be an emitter with 2D material that emits light energy in response to an electric field across the two electrodes. The photonic device may be a modulator with 2D material that modulates a property of an optical signal (e.g., the amplitude or phase) by modulating the amount of strain induced in the 2D material.

Integrated photonic device utilizing strained 2D material

Precision and chip contamination-free placement of two-dimensional (2D) material and van der Waals (VDW) layered materials accelerates both the study of fundamental properties and novel device functionality. The system transfers 2D materials utilizing a combination of a narrow transfer-stamper and viscoelastic and optically transparent film. Precise placement of individual 2D materials results in vanishing cross-contamination to the substrate. The 2D printer results in an aerial cross-contamination improvement of two to three orders of magnitude relative to state-of-the-art transfer methods from a source of average area sub um{circumflex over ( )}2. The transfer-stamper does not physically harm any micro/nanostructures preexisting on the target substrates receiving the 2D material such as, nanoelectronics, waveguides or micro-ring resonators. Such accurate and substrate-benign transfer method for 2D and VDW layered materials provides rapid device prototyping due to its high time-reduction, accuracy, and contamination-free process.

Two-dimensional material printer and transfer system and method for atomically layered materials

An integrated photonics computing system implements a residue number system (RNS) to achieve orders of magnitude improvements in computational speed per watt over the current state-of-the-art. RNS and nanophotonics have a natural affinity where most operations can be achieved as spatial routing using electrically controlled directional coupler switches, thereby giving rise to an innovative processing-in-network (PIN) paradigm. The system provides a path for attojoule-per-bit efficient and fast electro-optic switching devices, and uses them to develop optical compute engines based on residue arithmetic leading to multi-purpose nanophotonic computing.

Residue arithmetic nanophotonic system

A digital-to-analog converter has a first interface coupled to a second interface through one or more modulation circuits. The circuits include a first coupler connected to the first interface; a first waveguide with a first lead connected to the first coupler, a first end, and a first length running therebetween. The first lead and the first end are coupled by a first switch. The circuits also include: a second coupler connected to the first interface; a second waveguide having a second lead connected to the second coupler, a second end, and a second length running therebetween, the second lead and the second end coupled by a second switch along the second length; and an optical combiner connected to the ends of the waveguides. The second interface is connected to the optical combiner of the modulation circuits. Output from the second interface is an optical signal capable of carrying binary information.

Optical digital to analog converter using electro-modulated waveguides

An accelerator for modern convolutional neural networks applies the Winograd filtering algorithm in a wavelength division multiplexing integrated photonics circuit modulated by a memristor-based analog memory unit.

Optical convolutional neural network accelerator

The ability to rapidly identify symmetry and anti-symmetry is an essential attribute of intelligence. Symmetry perception is a central process in human vision and may be key to human 3D visualization. While previous work in understanding neuron symmetry perception has concentrated on the neuron as an integrator, the invention provides the coincidence detecting property of the spiking neuron can be used to reveal symmetry density in spatial data. A synchronized symmetry-identifying spiking artificial neural network enables layering and feedback in the network. The network of the invention can identify symmetry density between sets of data and present a digital logic implementation demonstrating an 8&#xd7;8 leaky-integrate-and-fire symmetry detector in a field-programmable gate array. The efficiency of spiking neural networks can be harnessed to rapidly identify symmetry in spatial data with applications in image processing, 3D computer vision, and robotics.

Identifying mirror symmetry density with delay in spiking neural networks

A photonic waveguide assembly has a first arm comprising a first photonic waveguide transmitting a first light, an optical refractive index modulator positioned about said first photonic waveguide to modulate the phase or amplitude, or combination thereof of the first light traveling in the first photonic waveguide; a second arm comprising a second photonic waveguide transmitting a second light; and a passive contact that contacts at least a portion of the second photonic waveguide of said second arm.

Optical digital to analog converter using seriated splitters

Precision and chip contamination-free placement of two-dimensional (2D) material and van der Waals (VDW) layered materials accelerates both the study of fundamental properties and novel device functionality. The system transfers 2D materials utilizing a combination of a narrow transfer-stamper and viscoelastic and optically transparent film. Precise placement of individual 2D materials results in vanishing cross-contamination to the substrate. The 2D printer results in an aerial cross-contamination improvement of two to three orders of magnitude relative to state-of-the-art transfer methods from a source of average area sub um{circumflex over (&#x2003;)}2. The transfer-stamper does not physically harm any micro/nanostructures preexisting on the target substrates receiving the 2D material such as, nanoelectronics, waveguides or micro-ring resonators. Such accurate and substrate-benign transfer method for 2D and VDW layered materials provides rapid device prototyping due to its high time-reduction, accuracy, and contamination-free process.

An electro-optical modulator using a graphene-based plasmonic slot is disclosed. The electro-optical modulator is comprised of a substrate layer, a dielectric spacer, a graphene layer, a first metal layer, and a second metal layer. The metal layers create a plasmonic slot that modulates between a light absorptive and light transparent state depending on the application of voltage across the modulator. Two or four graphene layers may be used to reduce power consumption and the size of the modulator.

Graphene-based plasmonic slot electro-optical modulator

Photonic data routing in optical networks is expected overcome the limitations of electronic routers with respect to data rate, latency, and energy consumption. However photonics-based routers suffer from dynamic power consumption, and non-simultaneous usage of multiple wavelength channels when microrings are deployed and are sizable in footprint. Here we show a design for the first hybrid photonic-plasmonic, non-blocking, broadband 5&#xd7;5 router based on 3-waveguide silicon photonic-plasmonic 2&#xd7;2 switches. The compactness of the router (footprint &#x3c;200 &#x3bc;m) results in a short optical propagation delay (0.4 ps) enabling high data capacity up to 2 Tbps. The router has an average energy consumption ranging from 0.1&#x2dc;1.0 fJ/bit depending on either DWDM or CDWM operation, enabled by the low electrical capacitance of the switch. The total average routing insertion loss of 2.5 dB is supported via an optical mode hybridization deployed inside the 2&#xd7;2 switches, which minimizes the coupling losses between the photonic and plasmonic sections of the router. The router's spectral bandwidth resides in the S, C and L bands and exceeds 100 nm supporting WDM applications since no resonance feature are required. Moreover, this hybrid photonic-plasmonic switch design is also suitable for 3 up to a few dozens of routing ports by simply cascading our 2&#xd7;2 switch with a specific pattern. Taken together this novel optical router combines multiple design features, all required in next generation high data-throughput optical networks and computing systems.

Hybrid photonic non-blocking wide spectrum WDM on-chip router

The present invention provides optical computing by means of fast Fourier transform Integration on Silicon On Insulator chip technology with implementation in the analog and temporal domain. This is done by cascading (N&#x2212;2) stages of delayed interferometers (couplers and phase shifters) where a parallel set of N time samples are taken and using the delay lines and phase of the optical components (constructive/deconstructive interference) the DFT is computed. The Optical Fast Fourier Transform (OFFT) design was built on passive components (2&#xd7;2 couplers: cascaded Mach Zehnder Interferometer) used for addition and subtraction through optical interference, waveguides with short path differences are used for phase shifting and waveguides with long path differences are used for signal delay based on the needed number of outputs. Since the OFFT is a system of imbalanced interferometers, there are additional bends designed to compensate for the difference in power ratios of the arms.

Growing community of inventors

Alexandria, VA, United States of America

Volker J Sorger