Electro-optical Logic Research Articles

Electro-Optic Hybrid Logic Gate Derived from a Silicon-Based Hybrid Surface Plasmon Polariton Waveguide

Electro-optic hybrid computing is a key research topic in high-performance computing. AND, OR and NON are the most basic computing units. Logic units, which are composed of a Mach Zehnder interferometer (MZI) and a micro ring resonator (MRR), have the issues of large size and poor thermal stability. To solve these problems, this paper discusses the design of AND, OR and NON basic logic units in compact electro-optic logics based on the principle of silicon-based hybrid surface plasmon polariton waveguides. By optimizing the parameters with the Finite Difference-Time Domain (FDTD), the simulation results show that the maximum insertion loss (IL) of the AND, OR and NON logic units is 5.1 dB, and the extinction ratio (ER) is at least 14.3 dB. The experimental simulation results provide a theoretical basis for the design of an electro-optic logic gate derived from a silicon-based hybrid surface plasmon polariton waveguide.

Electro-optical logic using dual-nanobeam Mach-Zehnder interferometer switches.

The maturity of integrated photonics enables many applications including high-performance computing. Digital photonic computing always considers resonator-based modulators as the key active components due to their compactness as compared to broad-spectrum Mach-Zehnder interferometers (MZIs). In this paper, we investigate the dual-nanobeam (NB) based MZI 2 × 2 switches with much smaller footprint for realizing electro-optical logic circuits. New logic gates and scalable circuits assisted by multiplexing techniques are proposed. Results show that the NB MZI is another promising candidate for electronic-photonic digital computing.

High-speed thermally tuned electro-optical logic gates based on micro-ring resonators

This work proposes electro-optical design of logic gates using micro-ring resonators (MRR). We achieve this through various combinations of MRRs. In order to modulate the rings, thermo-optic effect is utilized. The reported devices are completely CMOS-compatible and can be fabricated using existing technologies. We also provide static responses to explain the device working principles. By plotting dynamic response spectra, the performance of each device is examined. The proposed logic elements are able to operate at 0.4 Mbps.

Integrated multi-operand electro-optic logic gates for optical computing

Integrated optical computing has the potential to enhance the computation abilities in terms of computing speed and power consumption during the post-Moore's law era. As one of the widely investigated approaches, electro-optic logic uses electro-optic switches as the building blocks to achieve complex functions. In this paper, we propose and experimentally demonstrate a multioperand electro-optic logic gate that contains multiple active regions in a single gate to further increase the versatility of gates. Thus, one gate can be controlled by several electrical inputs simultaneously. The ability of multioperand logic gates is thoroughly explored. The detailed comparison shows that the proposed gate can largely improve the circuit performance in terms of the area, latency, power, and insertion loss. We believe the multioperand logic gate has the potential to contribute to a more compact and power-efficient integrated optical computing system.

A reconfigurable scheme for realization of electro-optical logic gate based on silicon-graphene Mach–Zhender interferometer

In this paper, we propose a reconfigurable scheme for implementation of an electro-optical logic gate by utilizing a Mach–Zehnder interferometer (MZI)-based structure. In order to achieve high performance and small footprint for the proposed logic gate, we have used a compact, broadband, low power and high speed MZI-based electro-optical switch which consists of a silicon-graphene slot waveguide as phase shifter in each arm of the MZI structure. Our design can perform electro-optical AND, OR and XOR logic functions in three different operational modes by using three electrical control signals. The functionality of the reconfigurable electro-optical logic gate is investigated with the help of eye diagram analysis for all three operational modes. Simulation results show that the proposed reconfigurable logic gate is able to work under at least 62.5 Gbit/s with high extinction ratio (ER) about 24.6 dB for transverse electric polarization mode at telecommunication wavelength of 1.55 [Formula: see text]m.

Dielectric-loaded graphene-based plasmonic multilogic gate using a multimode interference splitter.

In this paper, we propose a multilogic gate (MLG) by utilizing a dielectric-loaded graphene-based plasmonic waveguide (DLGPW) in the mid-infrared spectral region. The proposed MLG is composed of DLGPW-based switches and multimode interference (MMI) splitters and supports three logical operations-AND, XNOR, and NOR-simultaneously. First, by proper control of the graphene surface conductivity, a graphene plasmonic on-off switch is presented, and then a 3dB MMI splitter based on a DLGPW for a wavelength of 7.8μm is designed and investigated. Our studies show that electro-optical logic gates based on DLGPWs have not been reported to date. The structure of the presented MLG is very simple and CMOS-compatible. The calculated minimum extinction ratios (ER) for AND, XNOR, and NOR logic gates are 17.53dB, 53.43dB, and 17.53dB, respectively. Also, by some modifications, this structure can act as a NAND logic gate with an ER of 55.22dB. Compact footprint, high ER, and easiness of on-chip implementation are some advantages of the presented MLG.

Automated logic synthesis for electro-optic logic-based integrated optical computing.

Integrated optical computing attracts increasing interest recently as Moore's law approaches the physical limitation. Among all the approaches of integrated optical computing, directed logic that takes the full advantage of integrated photonics and electronics has received lots of investigation since its first introduction in 2007. Meanwhile, as integrated photonics matures, it has become critical to develop automated methods for synthesizing optical devices for large-scale optical designs. In this paper, we propose a general electro-optic (EO) logic in a higher level to explore its potential in integrated computing. Compared to the directed logic, the EO logic leads to a briefer design with shorter optical paths and fewer components. Then a comprehensive gate library based on EO logic is summarized. At last, an And-Inverter Graphs (AIGs) based automated logic synthesis algorithm is described as an example to implement the EO logic, which offers an instruction for the design automation of high-speed integrated optical computing circuits.

Multifunctional Microelectro-Opto-mechanical Platform Based on Phase-Transition Materials.

Along with the rapid development of hybrid electronic-photonic systems, multifunctional devices with dynamic responses have been widely investigated for improving many optoelectronic applications. For years, microelectro-opto-mechanical systems (MEOMS), one of the major approaches to realizing multifunctionality, have demonstrated profound reconfigurability and great reliability. However, modern MEOMS still suffer from limitations in modulation depth, actuation voltage, or miniaturization. Here, we demonstrate a new MEOMS multifunctional platform with greater than 50% optical modulation depth over a broad wavelength range. This platform is realized by a specially designed cantilever array, with each cantilever consisting of vanadium dioxide, chromium, and gold nanolayers. The abrupt structural phase transition of the embedded vanadium dioxide enables the reconfigurability of the platform. Diverse stimuli, such as temperature variation or electric current, can be utilized to control the platform, promising CMOS-compatible operating voltage. Multiple functionalities, including an active enhanced absorber and a reprogrammable electro-optic logic gate, are experimentally demonstrated to address the versatile applications of the MEOMS platform in fields such as communication, energy harvesting, and optical computing.

Flexible organic N-channel phototransistor and integrated logic devices

A flexible organic field-effect transistor (OFET) and flexible phototransistor have been fabricated using self-assembled single crystals of a small molecule, viz, N,N’-dioctyl-3,4,9,10-perylene tetracarboxylic diimide (PTCDI-C8). The solution processed single crystals of PTCDI-C8 with strong molecular ordering showed excellent OFET performances having mobility μ∼0.2cm2/Vs. The absence of grain boundaries, traps and intrinsically defect-free nature of the single crystals contributed to the improved device performances in PTCDI-C8 crystalline OFET. The device exhibited high sensitivity to photo-illumination with photoresponsivity value upto Ca. 3A/W and photo to dark current ratio ∼103. Both the transistor and photosensing characteristics of the OFET device were retained even under extreme bending of the flexible substrate, exhibiting robust mechanical flexibility of the OPT. To realize OFET based electro-optical logic circuits, we have suitably integrated the photo signal and electrical signal and demonstrated that binary NOT and OR operations could be performed on the OFET device with light as one of the input signal. The large area deposition of self-assembled organic single crystals with multifunctional activity, such as, photosensing with switching, signal amplification, and electro-optical logic operation opens up immense possibilities for flexible organic logic device and promises great potential for future low-cost plastic optoelectronic applications.

Moving toward optoelectronic logic circuits for visible light: a chalcogenide glass single-mode single-polarization optical waveguide switch

In this paper, we propose an arsenic trisulfide (As-S) optical waveguide switch-based logic gate mainly comprised of a photorefractive Sn1As20S79 waveguide core and a LiNbO3 crystal substrate. In combination with the unique optical stopping effect of Sn1As20S79, this device can realize logical operations on an electrical signal and an optical signal, holding promises to be applied in optoelectronic logic circuits. While most of the previous research on As-S has focused on applications in the infrared regime, this device operates at the visible wavelengths of 632.8 and 441.6 nm, which are the specific wavelengths for optical stopping. As the kernel part of this logic gate, an optical waveguide switch based on an electro-optic coupler is employed to control optical signals by electrical signals, providing a solid foundation of operation for an electro-optic logic function. Some crucial design specifications of the switch are optimized by means of simulation analysis. It is found that less than 10 V of applied voltage is sufficient to realize a satisfactory function of the switch. A coupling efficiency of 90% and an extinction ratio of greater than 10 dB are achieved by simulating the lightwave propagation in the waveguide switch. Since the waveguide structure of the switch has no upper cladding, it is different from that of a ridge waveguide or a buried waveguide, and is, thus, convenient to fabricate by only using UV exposure without etching. Our work will open new possibilities for photoelectric hybrid logical operation in visible light, and, thus, provide fertile ground for applications in programmable optical chips.

新型电光逻辑门的设计及计算机图形光谱

新型电光逻辑门的设计及计算机图形光谱

新型电光逻辑门的设计及计算机图形光谱

新型电光逻辑门的设计及计算机图形光谱

Design and theoretical investigation of a silicon-on-insulator based electro-optical logic gate device

A compact electro-optical “NOR” logic gate device based on silicon-on-insulator (SOI) platform is proposed and investigated theoretically. By introducing a hook-type waveguide, the signal could be coupled between the bus and hook-type waveguide to form an optical circuit and realize NOR logic gate. We can easily realize the NOR logical function by the voltage applied on the coupling components. The numerical simulation shows that a high coupling efficiency of more than 99% is obtained at the wavelength of 1550 nm, and the footprint of our device is smaller than 90 μm2. In addition, the response time of the proposed NOR logic gate is 3 ns with a switching voltage of 1.8 V. Moreover, it is demonstrated that such NOR logic gate device could obtain an extinction ratio of 21.8 dB. Thus, it has great potential to achieve high speed response, low power consumption, and small footprint, which fulfill the demands of next-generation on-chip computer multiplex processors.

Ultracompact electro-optical logic gates based on graphene–silica metamaterial

We propose and simulate numerically a permittivity-tunable metamaterial channel, which is composed of alternating layers of graphene and silica. The real part of the permittivity of the proposed metamaterial can be tuned from a positive value to a negative one for a broadband width. Furthermore, optical waves can pass through the metamaterial channel only when its permittivity is tuned to zero. Inspired by this intriguing property of the graphene–silica metamaterial, three basic electro-optical logic gates, including NOT, NOR, and NAND gates, were proposed and numerically investigated by using the finite element method. Taking advantage of the permittivity-tunable property of graphene, the working wavelength of the proposed electro-optical logic gates can be actively controlled by tuning the external voltage applied on the graphene–silica metamaterial. These tunable and ultracompact electro-optical logic gates could benefit the development of nanoscale optical devices for highly integrated photonic circuits.

Electro-optical logic gates based on graphene–silicon waveguides

In this paper, designs of electro-optical AND/NAND, OR/ NOR, XOR/XNOR logic gates based on cascaded silicon graphene switches and regular 2×1 multimode interference combiners are presented. Each switch consists of a Mach–Zehnder interferometer in which silicon slot waveguides embedded with graphene flakes are designed for phase shifters. High-speed switching function is achieved by applying an electrical signal to tune the Fermi levels of graphene flakes causing the variation of modal effective index. Calculation results show the crosstalk in the proposed optical switch is lower than −22.9dB within a bandwidth from 1510nm to 1600nm. The designed six electro-optical logic gates with the operation speed of 10Gbit/s have a minimum extinction ratio of 35.6dB and a maximum insertion loss of 0.21dB for transverse electric modes at 1.55μm.

Reconfigurable Electro-optic Logic Circuits Using Microring Resonator-Based Optical Switch Array

In this paper, we propose a reconfigurable electro-optic logic circuit, which can perform any combinatorial logic operations using a microring resonator (MRR)-based optical switching array. The operands are represented by electrical signals, which are applied to the corresponding MRRs to control their switching status. The operation results are directed to the output port in the form of light. For proof of concept, the circuit consisting of four thermooptic MRR-based optical switches is fabricated on the silicon-on-insulator (SOI) substrate using the commercial complementary metal-oxide-semiconductor (CMOS) fabrication process. Finally, several logic operations of four operands with the operation speed of 10 kb/s are demonstrated successfully.

Proposed ultralow-energy dual photonic-crystal nanobeam devices for on-chip N x N switching, logic, and wavelength multiplexing.

Silicon-on-insulator Mach-Zehnder interferometer structures that utilize a photonic crystal nanobeam waveguide in each of two connecting arms are proposed here as efficient 2 × 2 resonant, wavelength-selective electro-optical routing switches that are readily cascaded into on-chip N × N switching networks. A localized lateral PN junction of length ~2 μm within each of two identical nanobeams is proposed as a means of shifting the transmission resonance by 400 pm within the 1550 nm band. Using a bias swing ΔV = 2.7 V, the 474 attojoules-per-bit switching mechanism is free-carrier sweepout due to PN depletion layer widening. Simulations of the 2 × 2 outputs versus voltage are presented. Dual-nanobeam designs are given for N × N data-routing matrix switches, electrooptical logic unit cells, N × M wavelength selective switches, and vector matrix multipliers. Performance penalties are analyzed for possible fabrication induced errors such as non-ideal 3-dB couplers, differences in optical path lengths, and variations in photonic crystal cavity resonances.

Demonstration of reconfigurable electro-optical logic with silicon photonic integrated circuits

We demonstrate a scalable and reconfigurable optical directed-logic architecture consisting of a regular array of integrated optical switches based on microring resonators. The switches are controlled by electrical input logic signals through embedded p-i-n junctions. The circuit can be reconfigured to perform any combinational logic operation by thermally tuning the operation modes of the switches. Here we show experimentally a directed logic circuit based on a 2×2 array of switches. The circuit is reconfigured to perform arbitrary two-input logic functions.

Electro-optical logic application of multimode interference coupler by multivalued controlling

Electro-optical hybrid logic is a potential solution to implement both electrical and optical signal processing, which receives analog or digital, electrical or optical signals and produces logic signals in a desired manner. In light of the transfer matrix theory, we found that one can steer light into different output ports of a multimode interference coupler by controlling the phases in a multivalued manner on the image-extended arms. This implementation acts as an analog-to-digital convertor from electric domain to optical domain. Also, an electrical-to-optical 2-to-2(2) binary-coded decoder is described and examined by the 3D beam propagation method.

Dual-microring-resonator electro-optic logic switches on a silicon chip

We report dual-microring-resonator electro-optic logic switches using two embedded injection-type p-i-n diodes with dual electrical inputs on a silicon chip. Our matrix analysis and semiconductor device numerical simulations reveal OR (NOR) function electro-optic switching for the throughput- (drop-) port transmission at a probe wavelength near the resonance of the coupled identical microring resonators. We find that upon the dual electrical digital input states (1, 0) and (0, 1), the drop-port transmissions are related by reciprocity and thereby are identical, whereas the throughput-port transmissions are not reciprocity related and thus in general are non-identical. Our characterizations of initial fabricated devices on a silicon-on-insulator substrate, however, reveal that the proposed logic operations hinge on high fabrication fidelity of the coupled microring resonators.