Optical Logic Circuits Research Articles

Characterization of a four-channel surface plasmon polaritons emitter based on a combined grooves coupling structure using photoemission electron microscopy

In various functional devices relying on femtosecond surface plasmon polaritons (SPPs), actively controlling the propagation direction of the SPPs field is crucial for designing plasmon-based functional devices. This capability is particularly valuable in optical logic circuits and optical communication systems. In this study, we employed photoemission electron microscopy (PEEM) to conduct near-field imaging of the SPPs field generated by a novel combination of wide and narrow grooves etched on a flat silver film. Experimental results revealed that femtosecond SPPs fields excited by laser pulses with different linear polarizations (±45°) can be emitted in four distinct directions, showcasing the combined groove structure's potential as a four-channel SPPs emitter. Additionally, Finite-Difference Time-Domain (FDTD) simulations were utilized to model the time evolution envelope of SPPs modes excited by groove coupling structures irradiated with laser pulses of varying polarization directions. The physical mechanism behind the combined groove structures as a four-channel SPPs emitter was thoroughly analyzed, and the experimental findings closely aligned with the FDTD simulation results. This research is of significant importance for advancing novel ultra-fast micro-nano optoelectronic devices with exceptional properties and for constructing ultra-fast information processing systems in plasmonics nanocircuits.

Nonreciprocal reflection based on asymmetric graphene metasurfaces.

We propose a scheme to achieve controllable nonreciprocal behavior in asymmetric graphene metasurfaces composed of a continuous graphene sheet and a poly crystalline silicon slab with periodic grooves of varying depths on each side. The proposed structure exhibits completely asymmetric reflection in opposite directions in the near-infrared range, which is attributed to the pronounced structural asymmetry and its accompanying nonlinear effects. The obtained nonreciprocal reflection ratio, reaching an impressive value of 21.27 dB, combined with a minimal insertion loss of just -0.76 dB, highlights the remarkable level of nonreciprocal efficiency achieved by this design compared to others in its category. More importantly, the proposed design can achieve dynamic tunability by controlling the incident field intensity and the graphene Fermi level. Our design highlights a potential means for creating miniaturized and integratable nonreciprocal optical components in reflection mode, which can promote the development of the integrated isolators, optical logic circuits, and bias-free nonreciprocal photonics.

Vertical 1T’‐WTe2/WS2 Schottky‐Barrier Phototransistor with Polarity‐Switching Behavior

AbstractIn recent years, 2D reconfigurable phototransistors (RPTs) have been applied in broadband convolutional processing, retinomorphic hardware devices, and non‐volatile memorizers. However, there has been a lack of investigation into all‐2D Schottky junctions used in RPT with polarity control behavior. Herein, a vertically stacked multilayered WS2/WTe2 Schottky RPT is reported. The semimetal characteristics of 1T’‐WTe2 is designed to form a built‐in electric field of 69 meV across the heterojunction and WS2 exhibits gate‐tunable characteristics. Therefore, reconfigurable rectifying behavior and self‐driven bidirectional photo response can be achieved. The phototransistor possesses a gate‐tunable rectification ratio ranging from 10−2 to 105, and the corresponding logic half‐wave rectifier shows excellent switchable rectifying states. Under 635 nm illumination, the responsivity can be adjusted from −1325 to 430 mA W−1 with reversed signs. Meanwhile, the maximum power conversion efficiency is 2.84%, and the specific detectivity is 1.47 × 1012 Jones. The device shows both negative and positive responsivity with linear gate dependence within a voltage window of 10 V. Impressively, nonvolatile photovoltaic performance can be demonstrated by reversing short‐circuit current and open‐circuit voltage by applying and releasing pulsed gate voltage. Finally, reconfigurable polarization behavior, single‐pixel imaging, and the optical logic circuit are applicable to the heterostructure.

Non-covalent Supramolecular 1D Alternating Copolymer in Crystal toward 2D Anisotropic Photon Transport.

To realize organic integrated optoelectronic circuits, there is a need for anisotropic optical waveguides at the micro/nanoscale. Anisotropic alignment of one-dimensional (1D)-ordered supramolecular structures composed of light-emissive π-conjugated molecules in a crystal may meet the requirements of such waveguides. Here, we designed a bipyridyl-appended acrylonitrile-based π-conjugated molecule 1, which produced a 1D supramolecular polymer constructed through non-covalent bonding between a lone pair in 1 and a σ-hole in 1,4-diiodo-2,3,5,6-tetrafluorobenzene 2. The 1D copolymer of 1 and 2 is aligned horizontally with the two-dimensional (2D) crystal surface because of the angle-controlled supramolecular synthons. As a result of control over the non-covalent bonding direction, anisotropic photoluminescence and photon transport (optical waveguiding) characteristics are realized by orienting the transition dipole moment horizontally with respect to the 2D surface. Compared with the loss coefficient αL =52dBcm-1 for the long-axis direction of the 2D platelet cocrystal, a very large difference of αS =2111dBcm-1 is present in the crystal short-axis direction. The anisotropic waveguiding ability, αL/αS, is estimated to be 41, which is more than an order of magnitude greater than previously reported 2D platelet crystal waveguides. This supramolecular synthon provides an approach to designing anisotropic photon transporters and highly regulated optical logic circuits.

Near-infrared-II balanced ambipolar phototransistors realized by the optimized planar-heterojunction channel layer and charge-transfer-complex photosensitive layer

Ambipolar organic phototransistors (OPTs) operating in the near-infrared II (NIR-II) were successfully fabricated by using an organic planar-heterojunction channel layer and an organic–inorganic charge-transfer-complex (CTC) photosensitive layer. After optimizations of the ratio of vanadium pentoxide in CTC hybrid system and the substrate temperature of the deposited channel layer, the devices shows the most balanced output characteristics in the dark and under 1310 nm light illumination. These OPTs yielded significantly enhanced currents upon infrared light illumination with the photoresponsivities as high as 0.115 A/W for the n-channel, and 2.600 A/W for the p-channel, respectively. By analyzing the energy band of the heterojunction structure, the operating mechanisms of the balanced ambipolar NIR-II OPTs were derived. This work will be helpful to design the ambipolar infrared phototransistor and brings forward design thought of realization of optical complementary MOS logic circuits in the future.

A Review on Nonlinearity in Semiconductor optical Amplifer as Application in all Optical Signal Processing

The optical signal processing is the future of communication network. High speed all-optical packet routing is one of the essential applications of all-optical networks which is only possible with the development of all-optical logic technology. The development of optical logic elements and circuits are the steps in the growth of this technology and higher speed up to Tbit/sec can be achieved. The optical carrier frequency range 1013 to 1016 Hz provides enormous potential bandwidth with superior information carrying capacity over a long transmission distance. The need of higher capacity is continuing to encourage research in wavelength division multiplexing (WDM) and optical time division multiplexing (OTDM) based transmission systems, which need optical demultiplexing and wavelength conversion technology. Therefore, for high-speed optical networks, it is required to develop the all-optical gates to avoid power consumption in opto-electronics conversion. All optical logic gates perform computing operations, storage and transmission of data using light also known as optical computing. Optical technology promises massive upgrades in the efficiency and speed of computers, aswell as significant shrinkage in their size and cost. The non-linear optical device to be used i.e. Semiconductor Optical Amplifier (SOA) has proved to be the promising for all optical functions like wavelength conversion, logic functions, signal representation in all optical domain. Its compact size, high gain, fast response, strong refractive index variation, easy to manufacture and integration, and power efficiency makes it most optimum device for optical signal processing. In this paper, the application of SOA in optical processing is thoroughly reviewed and orient towards the latest application in neural networks.

Inverse-designed Metamaterials for On-chip Combinational Optical Logic Circuit

Inverse-designed Metamaterials for On-chip Combinational Optical Logic Circuit

Design of an ultra-compact photonic crystal based all optical XOR and NOT logic gates

Abstract Photonic crystals are periodic structures that are suitable for designing a variety of optical gates and logic circuits. In this paper, XOR and NOT logic gates are designed using two-dimensional square lattice photonic crystals. This structure consists of two inputs and one output, and the logical values ​​in the inputs and outputs are defined based on the amount of optical power. The plane wave expansion (PWE) method has been used in band structure calculations. The simulation results show that the proposed structure in a range of wavelengths has a photonic band gap that has a wavelength of 1.55 µm in this range. Therefore, the light sources placed in the inputs have a wavelength of 1.55 µm. Due to the use of a square structure that is easier to design and build, this structure is suitable for use in optically integrated circuits. Another advantage of this structure, in addition to its small dimensions, is the very low value of zero logic, which has increased the contrast ratio in the structure. The contrast ratio obtained in this structure is equal to 19.1 dB.

All-optical design for multiplexer and comparator utilizing hybrid plasmonic waveguides.

Two optical combinational logic circuits, namely a 2×1 multiplexer and a comparator utilized by hybrid plasmonic waveguides, have been designed, analyzed, and simulated standing on the finite element method (FEM) with a COMSOL software package version 5.5. Transmission at the output port versus a wavelength range from 800 to 2000 nm, the contrast ratio, the modulation depth, and the insertion loss are the aspects used to estimate the circuits' functionality. The realization of these circuits was based on the fundamentals of the constructive and destructive interferences among the input and the biasing ports. The multiplexer circuits require a single substructure with a measurement of 400×400nm and delivers the best transmission of 202.3% and 99.75% as a modulation depth, while the comparator performed by three substructures with a 1300×400nm overall size offers a 202.6% as the best transmission and 99.99% modulation depth in the Equality situation. The operating wavelength and the magnitude of the transmission threshold are 1310 nm and 0.3, respectively.

All-fiber nonvolatile broadband optical switch using an all-optical method.

Optical switches based on phase change materials have enormous application potential in optical logic circuits and optical communication systems. Integration of all-optical switching devices with optical fibers is a promising approach for realizing practical applications in enabling the optical fiber to transmit and process signals simultaneously. We describe an all-fiber nonvolatile broadband optical switch using an all-optical method. We use a single optical pulse to modulate the phase change material deposited on the tapered fiber to achieve logical control of the transmitted light. The response time of our optical switch is 80 ns for SET and 200 ns for RESET. Our optical switches can operate in the C-band (1530-1565 nm). The optical switching contrast is 40%. Our approach paves the way for all-optical nonvolatile fiber optic communication.

Novel optical XOR/OR logic gates based on topologically protected valley photonic crystals edges

Valley photonic crystals (VPCs) have provided a novel topological photonic platform to manipulate light. In this work, we construct zigzag and armchair domain walls using two-dimensional silicon VPCs, the edges between domains of opposite valley indices link to the corresponding topological invariant. We study the light transmission of these edges with defects and sharp bent corners. We design all-optical logic gates at telecommunication wavelength with both XOR and OR functions based on the valley-contrasting edges. Topologically protected waveguides own high transmission and backscattering-immune features, and the coupling process of different edge modes results in interference for logic functions. Compared with traditional photonic crystal logic gates, our device shows outstanding properties, including robust transmission, higher contrast ratio and more compact footprint. Furthermore, our work also shows the potential of topological photonics to be applied in optical logic circuits.

Ultra-compact terahertz all-optical logic comparator on GaAs photonic crystal platform

Photonic crystals are suitable structures for designing various types of optical logic circuits. In this paper, an all-optical comparator is designed and simulated using two-dimensional photonic crystals. A combination of linear and point defects has been used in the proposed structure. The small number of point defects and the use of simple linear defects make this comparator simple design. One of the important features of this comparator is that it uses two outputs to compare the input bits. A small structure is used for the proposed optical comparator. Also, this structure has a delay time of 0.07 ps, which is due to the very small size of the structure and the use of a small number of defects. The simulation results show that the bit rate for the proposed comparator is 3.33 Tb/s. Therefore, this structure can be suitable for use in high-speed logic circuits.

Optical Fiber Delivered Ultrafast Plasmonic Optical Switch.

Ultrafast optical switch based on plasmonic nanostructures has large application potentials in optical logic circuits and optical communication systems. Integration of plasmonic optical switching devices with optical fibers is a breakthrough for realizing practical applications in long‐range optical data transmission or communication techniques. Here, the incorporation of plasmonic optical switch devices onto the end facets of optical fibers is reported, so that the switched optical signals are generated by interaction between femtosecond laser pulses and plasmonic nanostructures on one end of the fiber, and are delivered via the fiber waveguide to the other end for detection or decoding. “Quenching” of localized surface plasmon in the gold nanowires by its interaction with band‐edge modulation in gold through strong optical excitation is the responsible photophysics. This work accomplishes for the first time the implementation of ultrafast plasmonic optical switch device on optical fiber tips for logic data transmission.

All optical logic gates based on nanoplasmonic MIM waveguides

In this paper, we propose and investigate some designs of basic plasmonic logic gates in two dimensional plasmonic waveguides with nanotube metal-insulator-metal waveguides using the numerical method of eigenmode expansion. These gates, including XOR, OR, NOT, and Feynman gate can be realized by changing geometrical parameters properly. Also, by cascading and combining these basic logic gates, any complex logic function can also be obtained providing the highly integrated optical logic circuits. The proposed logic gates have the broadband up to 300 nm and only spend the compact size as much as 2 µm×1.2 µm. Thus, the devices can be applied widely and significantly in optical computing and processing devices.

Ultra-High-Responsivity Vertical Nanowire-based Phototransistor under Standing-Wave Plasmon Mode Interaction Induced by Near-Field Circular OLED.

High-responsivity photodevices are strongly desired for various demanding applications, such as optical communications, logic circuits, and sensors. The use of quantum and photon confinement has enabled a true revolution in the development of high-performance devices. Unfortunately, many practical optoelectronic devices exhibit intermediate sizes where resonant enhancement effects seem to be insignificant. Here we design and fabricate an ultra-high-responsivity organic-light-emitting-diode-induced nanowire resonance phototransistor (ONRPT) based on standing-wave resonance in the nanoscale cavity, subjected to a near-field light. Observations of the ONRPT in standing-wave resonance mode indicate a >104 enhancement in the on/off ratio and a six times higher subthreshold slope when compared with the ONRPT in non-resonance mode. The ONRPT, which leads itself to outstanding electrical and favorably stable performance, opens up a plethora of opportunities for high-efficiency energy devices and allows for nanowire applications in the solar cell, piezo-photonic detectors, and optical modulators.

A Novel Proposal for All-Optical OR/AND Gate Using Nonlinear Photonic Crystal Ring Resonators

AbstractIn this paper, we aim to design an all-optical structure that can be employed as optical OR/AND logic gates. To do so, a nonlinear photonic crystal-based ring resonator will be designed whose resonant wavelength depends on the variation of optical intensity. Then, by adding some optical waveguides, the optical logic circuit structure will be obtained that can function as optical OR/AND logic gates. The maximum time delay for the proposed structure is about 1.5 ps. Total footprint of the proposed structure is about 372 mm2. The proposed structure has lower time delay, lower footprint and lower optical input power compared with previously proposed structures.

Nanoscale Optical Logic Circuits by Single-Step FRET

We propose a method for implementing nanoscale optical logic circuits via single-step Forster resonance energy transfer (FRET). Use of single-step FRET enabled circuits with simple design and high expandability. Two kinds of FRET gates, a YES gate and a NOT gate, were used to modulate fluorescence output signals based on light inputs. Various logic circuits could be implemented by connecting FRET gates on a DNA structure. The experimental results demonstrated that FRET gates for two kinds of input lights were constructed, and that logic circuits executing the AND and OR operations produced fluorescence signals as outputs.

Highly transparent phototransistor based on quantum-dots and ZnO bilayers for optical logic gate operation in visible-light.

Highly transparent optical logic circuits operated with visible light signals are fabricated using phototransistors with a heterostructure comprised of an oxide semiconductor (ZnO) with a wide bandgap and quantum dots (CdSe/ZnS QDs) with a small bandgap. ZnO serves as a highly transparent active channel, while the QDs absorb visible light and generate photoexcited charge carriers. The induced charge carriers can then be injected into the ZnO conduction band from the QD conduction band, which enables current to flow to activate the phototransistor. The photoexcited charge transfer mechanism is investigated using time-resolved photoluminescence spectroscopy, scanning Kelvin probe microscopy, and ultraviolet photoelectron spectroscopy. Measurements show that carriers in the QD conduction band can transfer to the ZnO conduction band under visible light illumination due to a change in the Fermi energy level. Moreover, the barrier for electron injection into the ZnO conduction band from the QD conduction band is low enough to allow photocurrent generation in the QDs/ZnO phototransistor. Highly transparent NOT, NOR, and NAND optical logic circuits are fabricated using the QDs/ZnO heterostructure and transparent indium tin oxide electrodes. This work provides a means of developing highly transparent optical logic circuits that can operate under illumination with low-energy photons such as those found in visible light.

A spatially pinned surface plasmon through short-circuiting electronic oscillation in waveguide-sustained SPPs

A spatially pinned surface plasmon is constructed by connecting a gold nanoshell grating with a planar gold nanofilm, forming a periodical array of gold nanoloops. Dramatic electric field modulation and high charge carrier density on the contact sites enable balanced plasmonic electron distribution over the spatially pinned nanostructures. Compared with its counterpart, spacer-supported double-layer surface plasmon polaritons (SPPs), the pinned structure not only changed the electronic oscillation channels but also short-circuited the propagating SPPs at the top and bottom interfaces. Ultrafast spectroscopic dynamics identified a much-extended relaxation lifetime of the pinned plasmon and revealed a holding time as long as 1.3 ps for the double-layer SPPs, which was sustained by microcavities based on distributed optical feedback. These results introduced a new type of surface plasmon and a new design of time retarders for optical logic circuits.

Methods for Reducing Power and Area of BDD-Based Optical Logic Circuits

Methods for Reducing Power and Area of BDD-Based Optical Logic Circuits