Optical Gate Research Articles

All-type optical logic gates using plasmonic coding metamaterials and multi-objective optimization.

In this article, we propose a multiport plasmonic system (MPS) for implementing all-type logic gates based on coding metamaterials and inverse design technology. Compared to traditional plasmonic logic gates, the coding metamaterials based on metal-dielectric-metal (MDM) structures provide powerful programmability for manipulating electromagnetic (EM) waves and have a compact footprint (0.8 µm × 1.1 µm) for integration. To improve the performance of logic gates, the nondominated sorting genetic algorithm version II (NSGA-II) are used to optimize the distributions of coding metamaterials. After the optimization, the simulation results show that all types of logic gates (AND, OR, NOT, NAND, NOR, XNOR, and XOR) can be obtained with an operating wavelength of 1.31 µm. The maximum extinction ratios between logic states "1" and "0" reach 10.15 dB, 57.54 dB, 43.25 dB, 20.76 dB, 10.42 dB, 24.04 dB, and 27.74 dB for the AND, OR, NOT, NAND, NOR, XNOR, and XOR gates, respectively. Moreover, wavelength-tunable logic operations are also demonstrated to work within a wide spectrum. Our proposed plasmonic system not only provides a universal scheme for implementing all-type compact logic gates for optical processing and computing but also demonstrates effective applications of inverse design in nanophotonic devices.

A General Synthetic Approach of Organic Lateral Heterostructures for Optical Signal Converters in All-Color Wavelength

A General Synthetic Approach of Organic Lateral Heterostructures for Optical Signal Converters in All-Color Wavelength

All-optical NOR and NOT logic gates based on ring resonator-based plasmonic nanostructures

In this paper, compact all-optical plasmonic NOR and NOT gates have been proposed. The structures are based on metal-insulator-metal waveguides coupled to different plasmonic ring resonators. The fundamental structure used for design of the mentioned logic gates is based on T-shaped switches which consists of circular and octagon shaped plasmonic ring resonators (PRR). The simulation results show that the value of contrast ratios of NOR and NOT gates for circular-shaped PRRs are 23.37 and 19.42 dB and the value of contrast ratios of NOR and NOT gates for octagon-shaped PRRs are 24.37 and 23.12 dB, respectively. Also, the maximum transmission ratios of octagon- and circular-shaped PRR at the ON condition are about 82% and 76%, respectively. The proposed logic gates have been simulated using finite difference time domain (FDTD) method. It is observed that the octagon-shaped gates have higher transmission ratios and lower loss than the circular-shaped gates. The size of the NOT gates based on the circular- and octagon-shaped PRRs is 0.4422 µm2 and 0.4775 µm2, respectively. Also, the size of the NOR gate based on the circular- and octagon-shaped PRRs is 0.8645 µm2 and 0.9176 µm2, respectively. These optical logic gates can be used as key components in optical communications and for designing compact plasmonic devices.

Photonic schemes of distribution and reconstruction of an entangled state from hybrid entanglement between polarization and time-bin via quantum dot

We propose photonic schemes for the distribution and reconstruction of a two-qubit entangled state using a hybrid entangled state under a noisy quantum channel. First, to generate a hybrid entangled state correlated with polarizations and time-bins, we employ a quantum dot (QD)-cavity system (nonlinear optical gate) and linear optical devices to implement controlled operation. These schemes can achieve the distribution and reconstruction of a two-qubit entangled state from hybrid entanglement by utilizing only linear optical devices without a QD-cavity system (i.e., a nonlinear optical device) for users who want to share an entangled state under a noisy quantum channel. For a feasible realization of the proposed schemes, we analyze the interaction between the photons and QD-cavity system and demonstrate the experimental conditions under which the reliable performance of the QD-cavity system is achieved.

Employing MZI-SOA to Design and Simulate the Optical OR Gate at A High Bit Rates of 250 Gbps

Employing MZI-SOA to Design and Simulate the Optical OR Gate at A High Bit Rates of 250 Gbps

Design, simulation of XOR / XNOR and AND logic gates using the optical two-circle switch

In this paper, first, the optical two-circle switch (OTCS) and then, the XOR / XNOR and AND logic gates were designed, simulated, and optimized. The OTCS designed structure consisted of two rectangular waveguides and two optical circles between them. The light enters from one waveguide, and due to the coupling between the waveguide and the ring, it enters the circle in case of constructive interference, transmitted to the adjacent circle, and finally, transferred to another waveguide. If it is possible to change the properties of the circle in such a way that there is no constructive interference in it, the coupling of the light from the first waveguide to the circle will not occur, therefore the light will come out from the other side of the first waveguide. The continuity condition of electromagnetic fields at the boundary between rectangular and ring waveguides and the scattering condition has been used in all simulation boundaries to simulate this structure. By optimizing the size and type of material in the core and cladding the waveguides and circles, up to 90 percent of input waves were observed from the output of the second waveguide with the barium titanate core. This occurs as a result of coupling modes between waveguides and circles. In the second step, by applying transverse voltage and changing the refractive index, the conditions of constructive interference in the ring were eliminated, and the coupling between the rectangular waveguide and the circle did not occur. As a result, up to 85 percent of the light exited from the end of the first rectangular waveguide. This change of output power from the first to the second waveguide and vice versa can transform the designed structure into a two-state voltage-controlled optical switch; by putting two of these switches together in a row, optical logic gates of XOR / XNOR and AND are simulated and then optimized.

Near-Zero-Index Slabs on Bloch Surface Wave Platform for Long-Range Directional Couplers and Optical Logic Gates.

Near-zero-index materials and structures, with their extraordinary optical behaviors of phase-free propagation resulting in directional radiation, provide a possible approach for directional coupling and optical logic gates in photonic integrated circuits. However, the radiation from the near-zero-index structures is limited to a short range of a few hundreds of nanometers. A Bloch surface wave (BSW), an electromagnetic surface wave that can be excited at the interface between an all-dielectric multilayer and a dielectric medium with a low-loss optical mode, provides a solution to increase the propagation length. In this work, we present a nanostructured near-zero-index slab integrated on the all-dielectric metal-free BSW platform for long-range surface wave radiation. By employing the long-range directional surface-wave radiation, a directional coupler and optical logic gates based on the BSW near-zero-index slabs are realized. The proposed directional couplers achieve long coupling distances (the electric-field magnitude ratio between the input slab and output slab is 0.22 with a 50 μm coupling distance), which is 2 orders of magnitude longer than that of conventional directional couplers based on evanescent wave coupling. By controlling the interference pattern of the BSW between the slabs, the XOR logic gate is experimentally demonstrated with a significant extinction ratio of 27.9 dB at telecommunications wavelengths. The BSW near-zero-index logic gates and the directional coupler with long-range light propagation provide an approach to the development of photonic integrated circuits and metal-free surface wave-based applications.

Ultrafast measurement of a single-photon wave packet using an optical Kerr gate.

Ultrafast quantum optics with time-frequency entangled photons is at the forefront of progress towards future quantum technologies. However, to unravel the time domain structure of entangled photons and exploit fully their rich dimensionality, a single-photon detector with sub-picosecond temporal resolution is required. Here, we present ultrafast single-photon detection using an optical Kerr gate composed of a photonic crystal fiber (PCF) placed inside a Sagnac interferometer. A near-rectangle temporal waveform of a heralded single-photon generated via spontaneous parametric down-conversion is measured with temporal resolution as high as 224 ± 9 fs. The large nonlinearity and long effective interaction length of the PCF enables maximum detection efficiency to be achieved with only 30.5 mW gating pulse average power, demonstrating an order-of-magnitude improvement compared to optical gating with sum-frequency generation. Also, we discuss the trade-off relationship between detection efficiency and temporal resolution.

Precise Synthesis of Organic Heterostructures via the Synergy Approach of Polymorphism and Cocrystal Engineering for Optical Applications

Comprehensive SummaryOrganic heterostructures that can integrate the physiochemical properties of two or more substances have attracted widespread attention in the field of optoelectronics. However, the epitaxial growth process between different organic material molecules is unpredictable, and the precise synthesis of organic heterostructures is still particularly challenging. Herein, through the synergy approach of polymorphism and cocrystal engineering, a series of organic branched heterostructures have been successfully prepared. Interestingly, by simply adjusting the solvent ratio, different crystalline phases of perylene microplates can be epitaxially grown on the perylene‐OFN cocrystal microwires, which provides a feasible approach for the preparation of organic heterostructures. Meanwhile, these as‐prepared organic branched heterostructures can realize multi‐channel and multi‐color emission, and act as optical logic gates, which promotes the multifunctional integrated optoelectronics.

High-Transmittance Femtosecond Optical Kerr Gate with Double Gate Pulses Based on Birefringence Effect

An optical Kerr gate (OKG) is an ultrafast optical switch based on the optical Kerr effect. The performance of a conventional OKG depends mainly on Kerr materials. Traditional Kerr materials do not demonstrate both large optical nonlinearity and an ultrafast response time. Therefore, the performance of a conventional OKG is limited by an inherent trade-off between high signal transmittance and fast switching time, which limits its application in many fields. We propose an improved femtosecond OKG with double gate pulses, based on the use of a birefringent crystal to realize an ultrashort switching time, even with a slow-response optical Kerr medium. We assessed the dependence of the double gate pulsed OKG (D-OKG)’s performance on the intensity ratio of the double gate pulses. A transmittance of 50% and a switching time of 142 fs were achieved. The D-OKG is convenient to construct, and its integrated performance is superior to that of a conventional OKG.

Simulation of reconfigurable double-input optical gates based on a microring flower-like structure, part II. Combinational logic gates.

A microring flower-like architecture is introduced to obtain optical logic gates that can be reconfigured. The proposed design can operate as a time-division multiplexer, a half adder/subtractor, and an optical single bit comparator circuit. The optical pump pulses modulate the microring resonators in this arrangement. Green lasers with a resonant wavelength of 532 nm are used to generate the optical pump pulses. To theoretically analyze the structure, the signal flow graph approach is applied. The proposed structure's performance is investigated by calculating certain figures of merit for the resulting output data streams. Outputs of the presented combinational logic gates are optimized by designing the most proper geometry of flower-like structure and simultaneously by opting for the best input port to drop port's optical path. It is demonstrated that proper distinguishing between 0 and 1 levels occurs in the output. The compact structure proposed is simple, expandable, and reconfigurable. The proposed structure can be used as a key component in high-speed optical networks, according to simulation results.

All-optical logic gate computing for high-speed parallel information processing

Optical computing and optical neural network have gained increasing attention in recent years because of their potential advantages of parallel processing at the speed of light and low power consumption by comparison with electronic computing. The optical implementation of the fundamental building blocks of a digital computer, i.e. logic gates, has been investigated extensively in the past few decades. Optical logic gate computing is an alternative approach to various analogue optical computing architectures. In this paper, the latest development of optical logic gate computing with different kinds of implementations is reviewed. Firstly, the basic concepts of analogue and digital computing with logic gates in the electronic and optical domains are introduced. And then a comprehensive summary of various optical logic gate schemes including spatial encoding of light field, semiconductor optical amplifiers (SOA), highly nonlinear fiber (HNLF), microscale and nanoscale waveguides, and photonic crystal structures is presented. To conclude, the formidable challenges in developing practical all-optical logic gates are analyzed and the prospects of the future are discussed.

Parametric data-driven optimization approach on plasmonic based ring resonator

In this paper, a plasmonic based ring resonator is being investigated. The metallic portion of plasmonic waveguide is chosen to be silver while the insulating material is air. The structure is numerically analyzed through Finite Difference in Time Domain (FDTD) method. To accurately model the relationship between the design parameter (radius of the ring) and the resonance condition of the resonator, a Machine Learning (ML) approach is applied. The ML model is trained on a dataset and tested for obtained results. The simulated results show that the proposed model is able to achieve the accuracy of prediction. The data driven optimization technique is being used for finding out the appropriate resonance condition of ring resonator. The proposed model is able to achieve good prediction accuracy (>90 %). The predicted result can be utilized in designing desired plasmonic devices like sensors, splitter, optical gates etc.

Cryptographic Circuit Technology Consisting of Optical Logic Gates

Cryptographic Circuit Technology Consisting of Optical Logic Gates

Actual origin and precise control of asymmetrical hysteresis in an individual CH3NH3PbI3 micro/nanowire for optical memory and logic operation.

Although CH3NH3PbI3 can present an excellent photoresponse to visible light, its application in solar cells and photodetectors is seriously hindered due to hysteresis behaviour. Moreover, for its origin, there exist different opinions. Herein, we demonstrate a route to realize precise control for the electrical transport of a single CH3NH3PbI3 micro/nanowire by constructing a two-terminal device with asymmetric Ag and C electrodes, and its hysteresis can be clearly identified as a synergistic effect of the redox reaction at the interface of the Ag electrode and the injection and ejection of holes in the interfacial traps of the C electrode rather than its bulk effect. The device can show superior bias amplitude and illumination intensity dependence of hysteresis loops with typical bipolar resistive switching features. Thus, an excellent multilevel nonvolatile optical memory can be effectively realized by the modulation of the illumination and bias, and moreover a logic OR gate operation can be successfully implemented with voltage and illumination as input signals as well. This work clearly reveals and provides a new insight of hysteresis origin that can be attributed to a synergistic effect of two asymmetrical electrode interfaces, and therefore precisely controlling its electrical transport to realize an outstanding application potential in multifunctional devices integrated with optical nonvolatile memory and logic OR gate operation.

Periodic structure containing host hyperbolic material for nano-guiding, sensing and imaging applications

In this simulation work, we have theoretically proposed a design of hyperbolic material-based ternary multilayer structure of plasma photonic crystal comprised of dielectrics and plasma materials. The optical properties have been analyzed with the help of transfer matrix method (TMM). The obtained spectra of reflection, transmission and absorption drawn with variation in filling fraction for the hyperbolic meta-material-based PC, are analyzed. By varying the filling fraction as f=0.1,0.2,0.3,0.4, it is found that at normalized frequency range, above 0.2, reflection is negligible. Thereafter, in higher normalized frequency, there exist a bandgap in a normalized frequency range 0.82–1.35. From the transmission spectra, it is noted that the transmission is nearly zero in lower normalized frequency range 0.0–0.2, then the transmission increases, and further decreases with formation of a bandgap. On the other-hand, the absorption is nearly 90% at lower normalized frequency region; and at higher normalized frequency, a zero-absorption band is obtained. Thus, we obtain an enlarged PBG in the normalized frequency range 0.82 to 1.35, where the zero-absorptionband for normal incidence also occurs at low frequency. The absorption increases with an increase in the filling fraction. All these results are in a good agreement with those reported earlier by the researchers. The insights of the present article can be employed in design of tunable optical filter, optical window, optical logic gate, broadband reflector, and absorption-based devices. The article can also be useful in the investigations on nano-guiding, sensing and imaging applications.

Chelation-activated ultralong room-temperature phosphorescence and thermo-/excitation-dependent persistent luminescence.

Multidentate chelation effect can be used to activate the ultralong room-temperature phosphorescence and stabilize the triplet excitons. The as-synthesized cadmium(II) based complexes further exhibit thermo- and excitation-dependent persistent luminescence as potential for optical logic gate.

All-optical logic devices based on black arsenic–phosphorus with strong nonlinear optical response and high stability

The Kerr nonlinearity in two-dimensional (2D) nanomaterials is emerging as an appealing and intriguing research area due to their prominent light processing, modulation, and manipulation abilities. In this contribution, 2D black arsenic-phosphorus (B-AsP) nanosheets (NSs) were applied in nonlinear photonic devices based on spatial self-phase modulation (SSPM) method. By applying the Kerr nonlinearity in 2D B-AsP, an all-optical phase-modulated system is proposed to realize the functions of “on” and “off” in all-optical switching. By using the same all-optical phase-modulated system, another optical logic gate is proposed, and the logical “or” function is obtained based on the 2D B-AsP NSs dispersions. Moreover, by using the SSPM method, a 2D B-AsP/SnS₂ hybrid structure is fabricated, and the result illustrates that the hybrid structure possesses the ability of the unidirectional nonlinear excitation, which helps in obtaining the function of spatial asymmetric light propagation. This function is considered an important prerequisite for the realization of diode functionalization, which is believed to be a factor in important basis for the design of isolators as well. The initial investigations indicate that 2D B-AsP is applicable for designing optical logical devices, which can be considered as an important development in all-optical information processing.

Design and analysis of an optical three-input AND gate using a photonic crystal fiber.

In this paper, a three-input AND logic gate is employed using a 2D photonic crystal T-shaped waveguide using a silicon in an air medium. In contrast to other gates, the key functions of employing an AND gate are recognition, error correction, code conversion, data encryption/decryption, and arithmetic operations. The proposed footprint is 8.4µm×5.4µm, which is a modest size. The performance of the proposed AND gate is investigated by employing the finite-difference time-domain approach, and the outputs are validated at wavelength (λ) of 1.55 µm. The outcomes clearly show the higher contrast ratio (CR) of 24.533 dB, and the worst case CR of is 8.6 dB; transmission efficiency values for minimum and maximum values are 19.6% and 142%; reaction time is 26 fs; insertion loss is 1.52 dB; and bit rate is 38.4 Tbps, which can be used in high-speed optical signal processing. The suggested circuit's primary objective is to consume minimal space and possess high CR.

10-Hz, 636-ps, 1064-nm, all polarization-maintaining fiber front-end based on ultrafast optical fiber pulse chopping

We demonstrate a robust 10-Hz, 1064-nm, all polarization-maintaining (PM) fiber laser front-end for a joule-level solid-state amplification system applying ultrafast optical pulse chopping. A 1064-nm single frequency continuous wave (CW) laser is chopped by an in-line acousto-optic modulator (AOM) to generate ∼7 ns duration pulses at 500-kHz repetition rate, followed by a Sagnac loop (SL) consisting of a 50:50 PM fiber coupler and an electro–optical (EO) phase modulator, which further shortens the pulse duration from 7 ns to 636 ps via a passively fixed optical chopping gate. Finally, the pulse energy is amplified to the sub-µJ level and its repetition rate is further reduced to 10-Hz by another in-line AOM stage. This 10-Hz, 636-ps, sub-µJ level fiber laser realized in an all-PM-fiber configuration can be used as a robust front-end for joule-level solid-state amplification and follow-on nonlinear frequency conversion experiments.