All-optical XOR Research Articles

Performance investigation of 120 Gb/s all-optical logic XOR gate using dual-reflective semiconductor optical amplifier-based scheme

Reflective semiconductor optical amplifiers (RSOAs) use an anti-reflective coating on the front facet and a high reflectivity coating on the rear facet to produce a higher gain than conventional SOAs. In this paper, this potential is exploited to numerically investigate the ultrafast performance of an all-optical logic XOR gate implemented using a dual-RSOA-based scheme at a data rate of 120 Gb/s. The simulation results demonstrate that the XOR gate is capable of operating at 120 Gb/s with better performance than when using conventional SOAs.

On solving the 1 + 1 routing, wavelength and network coding assignment problem with a bi-objective integer linear programming model

Network coding techniques have been viewed as the promising venue to improve the network efficiency and indeed, have been widely explored in the realm of failure recovery in optical networks. The combination of near-instantaneous recovery achieved by dedicated protections and capacity efficiency enabled by network coding brings about new opportunities to challenge the well-established trade-off of trading speed recovery for capacity efficiency and vice versa. In this context, the use of all-optical XOR network coding has reshaped the traditional 1 + 1 optical path protection in transparent WDM optical networks and established a new problem, called, 1 + 1 routing, wavelength and network coding assignment (1 + 1 RWNCA) as the extension of the conventional 1 + 1 routing and wavelength assignment (1 + 1 RWA). In this paper, we propose a bi-objective integer linear programming model of the 1 + 1 RWNCA problem aiming at minimizing the wavelength resources as the primary objective and simultaneously minimizing the wavelength link usage as the secondary objective. Our formulation uses a weighting method to combine two objectives into an integrated one and we provide insights on setting up the weight vectors to capture the priority of individual objectives. The effectiveness of our integrated objective model in comparison with reference designs based on the single-objective model, 1 + 1 RWA and 1 + 1 RWNCA, is numerically evaluated on different realistic topologies and traffic sets. Extensive simulation highlights that our proposal uses as efficient as around $$60\%$$ of the required wavelength link resources of reference designs and simultaneously achieve the highest performance on the primary objective of minimizing the wavelength resources while its computation time is a few time longer than its single objective counterpart model.

All‐optical NOT and XOR logic gates using photonic crystal nano‐resonator and based on an interference effect

In this study, a small size, low power, simple and high contrast ratio (CR) structure was designed and simulated to use in photonic crystal-based all-optical logic gates. This structure can be used for both all-optical logic NOT and XOR gates. The suggested structure is composed of three waveguides and a nano-resonator. The nano-resonator was designed by removing two dielectric rods. For use as an optical NOT logic gate, one of the input ports enters the control signal. In this case, the CR between logic levels `0' and `1' is 20.53 dB, which is higher than that of the provided gates based on structures published recently. The CR for the XOR gate is 19.95 dB. The response time to the input signal of the designed gate is 0.466 ps. The simplicity of the structure, small size, and high CR are the advantages of this structure compared to previously provided logic gates. The results have proven a superior prospect for the proposed structure to use in all optical integrated circuits.

Ultra-compact all-optical phase-controlled NAND, OR, XOR, XNOR, and NOT multi-function logic gate

We propose a novel multi-function logic gate in order to attain all NAND, OR, XOR, XNOR, and NOT logic functions in a single structure with controlling the phase of input lights. Beam propagation analysis illustrates that the highest insertion loss of structure is − 0.05 dB in whole C-band. The output on–off logic level contrast ratio for NAND, OR, XOR, XNOR, and NOT logic functions are 28.2, 28.2, 30.2, 30.2, and 30.2 dB, respectively. The structure which is composed of one multimode interference region with ultra-small size of 1.5 µm × 12.2 µm is a promising candidate for ultra-compact systems.

Fano Resonance Excited All-Optical XOR, XNOR, and NOT Gates with High Contrast Ratio

We have presented all-optical XOR, XNOR, and NOT gates using metal-insulator-metal (MIM)-coupled ring resonator. The performance of the device is evaluated by finite difference in time-domain (FDTD) method. The proposed gate utilizes a unique phenomenon of Fano resonance to excite logic OFF/ON state. Fano resonance has quite asymmetric resonance profile and the transmission spectrum of Fano profile abruptly drops to a minimum value at the resonance condition. Due to this unique resonance phenomenon, a large value of contrast ratio is obtained. The proposed XNOR gate offers a contrast ratio (C.R.) of 20.66 dB while XOR and NOT gates offer C.R. 12.8 and 18.8 dB respectively. The variation of contrast ratio is also studied against different input wavelength and it is reported that the obtained value of contrast ratio is an optimum value for the proposed structure. The device is compact sized with small dimension 0.31 λ02, where λ0 = 1.55 μm. The proposed device opens up the avenues for designing on-chip optical gates in the field of high-speed optical communication networks.

Realization of XNOR logic function with all-optical high contrast XOR and NOT gates

In this article, we propose the realization of XNOR logic function by using all-optical XOR and NOT logic gates. Initially, both XOR and NOT gates are designed, simulated and optimized for high contrast outputs. T-shaped waveguides are created on the photonic crystal platform to realize these logic gates. An extra input is used to perform the inversion operation in the NOT gate. Inputs in both the gates are applied with out of phase so as to have a destructive interference between them and produce negligible intensity for logic ‘0'. The XOR and NOT gates are simulated using Finite Difference Time Domain method which results with a high contrast ratio of 55.23 dB and 54.83 dB, respectively at a response time of 0.136 ps and 0.1256 ps. Later, both the gates are cascaded by superimposing the output branch of the waveguide of XOR gate with the input branch of the waveguide of NOT gate so that it can be resulted with compact size for XNOR logic function. The resultant structure of XNOR logic came out with the contrast ratio of 12.27 dB at a response time of 0.1588 ps. Finally, it can be concluded that the proposed structures with fair output performance can suitably be applied in the design of photonic integrated circuits for high speed computing and telecommunication systems.

On optimal designs of transparent WDM networks with 1 + 1 protection leveraged by all-optical XOR network coding schemes

Abstract Network coding techniques are seen as the new dimension to improve the network performances thanks to the capability of utilizing network resources more efficiently. Indeed, the application of network coding to the realm of failure recovery in optical networks has been marking a major departure from traditional protection schemes as it could potentially achieve both rapid recovery and capacity improvement, challenging the prevailing wisdom of trading capacity efficiency for speed recovery and vice versa. In this context, the maturing of all-optical XOR technologies appears as a good match to the necessity of a more efficient protection in transparent optical networks. In addressing this opportunity, we propose to use a practical all-optical XOR network coding to leverage the conventional 1 + 1 optical path protection in transparent WDM optical networks. The network coding-assisted protection solution combines protection flows of two demands sharing the same destination node in supportive conditions, paving the way for reducing the backup capacity. A novel mathematical model taking into account the operation of new protection scheme for optimal network designs is formulated as the integer linear programming. Numerical results based on extensive simulations on realistic topologies, COST239 and NSFNET networks, are presented to highlight the benefits of our proposal compared to the conventional approach in terms of wavelength resources efficiency and network throughput.

New designs of a complete set of Photonic Crystals logic gates

In this paper, we introduce new designs of all-optical OR, AND, XOR, NOT, NOR, NAND and XNOR logic gates based on the interference effect. The designs are built using 2D square lattice Photonic Crystal (PhC) structure of dielectric rods embedded in air background. The lattice constant, a, and the rod radius, r, are designed to achieve maximum operating range of frequencies using the gap map. We use the Plane Wave Expansion (PWE) method to obtain the band structure and the gap map of the proposed designs. The operating wavelengths achieve a wide band range that varies between 1266.9 nm and 1996 nm with center wavelength at 1550 nm. The Finite-Difference Time-Domain (FDTD) method is used to study the field behavior inside the PhC gates. The gates satisfy their truth tables with reasonable power contrast ratio between logic ‘1’ and logic ‘0’.

Reconfigurable all-optical NOT, XOR, and NOR logic gates based on two dimensional photonic crystals

Photonic crystals can be considered as one of the most important basis for designing optical devices. In this research, using two-dimensional photonic crystals with triangular lattices, ultra-compact logic gates are designed and simulated. The intended structure has the capability to be used as three logical gates (NOT, XOR, and NOR). The designed structures not only have characteristics of small dimensions which make them suitable for integrated optical circuits, but also exhibit very low power transfer delay which makes it possible to design high speed gates. On comparison with the previous works, our simulations show that at a wavelength of 1.55μm, the gates indicate a time delay of about 0.1 ps and the contrast ratio for the XOR gate is about 30 dB, i.e., the proposed structures are more applicable in designing low error optical logic gates.

Leveraging the Survivable All-Optical WDM Network Design With Network Coding Assignment

This letter investigates a novel use of network coding (NC) in 1 + 1 protection for transparent wavelength-division multiplexing networks by utilizing a cost-effective all-optical XOR encoder/decoder. In applying this scheme, we introduce a new problem, called routing, wavelength, and NC assignment, and formulate it as the integer linear programming model, aiming at maximizing the network throughput under constrained bandwidth capacity. We evaluate our proposal on the realistic topology, COST239, with all-to-one traffic setting. The numerical results on studied case show that the our NC-based approach could support up to 30% traffic more than the conventional 1 + 1 protection.

All-optical XOR and OR by Mach-Zehnder Interferometer engineered photonic crystal fibers

In this paper, we present a numerical investigation of all-optical logic gates based on a Mach-Zehnder Interferometer (MZI) configuration of micro structured fibers, also known as photonic crystal fibers (PCF) under optical OOK (on-off keying). We determine several relevant quantities to characterize the system performance, such as transmission and extinction ratio as a function of the nonlinearity profile (β) added to one of the Mach-Zehnder Interferometer (MZI) arms. High-order effects such as third-order dispersion, intrapulse Raman scattering and self-steepening were included in the generalized nonlinear Schrödinger equation describing the pulse propagation. For this study, we used an optical pulse with a shape of hyperbolic secant of 100fs (femtosecond). A pumped laser with three power values was simulated. With critical power Pc=103.5kW (P=Pc), below the critical power P=90kW (P<Pc) and above the critical power P=110kW (P>Pc). We added a nonlinearity profile in one of the Mach-Zehnder Interferometer (MZI) arms. Nonlinearity profiles were expressed in terms of the parameter β. We studied three different profiles: constant, increasing and decreasing. Our results show that the proposed device can be used to obtain all-optical OR and XOR logic gates as well as logic functions A and A.B¯. The OR logic gate was the one which achieved the greatest FOMELG (Figure of Merit of Logic Gates) when using increasing profile with critical power (P0=103.5kW) for β=1.05 and FOMELG=15.68dB. The XOR logic gate presented the greatest FOMELG=7.75dB when using the decreasing profile with power below the critical (P0=90kW) for β=1.44. These results provide support for applications in all-optical networks.

All-optical logic gates in plasmonic metal–insulator–metal nanowaveguide with slot cavity resonator

We demonstrate the compact all-optical logic XOR and OR gates in subwavelength plasmonic metal–insulator–metal waveguides with slot cavity resonators, especially for telecommunication wavelengths, with an extinction ratio of 25 dB, which can provide nanoscale logic integrated circuits. The gates behavior is based on suppression or enhancement of resonant modes in a slot cavity resonator induced by a change in position of input ports. The performance of the gates is discussed analytically and verified by the numerical method of finite-difference time-domain (FDTD).

All-optical XOR and NAND logic gates based on plasmonic nanoparticles

In this paper, all-optical XOR and NAND logic gates based on gold disk-shaped nanoparticles have been proposed. The proposed structure consists of a non-periodic array of disk-shaped nanoparticles that are placed on SiO2 substrate. The gates function is based on the constructive and destructive interferences between the input signals. For the NAND gate the phase difference between the input signals has been used to create a destructive interference. The most advantages of these structures are subwavelength dimensions and high contrast ratio of about 26dB and 24dB for the XOR and NAND logic gates, respectively.

Ultracompact all-optical logic gates based on nonlinear plasmonic nanocavities

Abstract In this study, nanoscale integrated all-optical XNOR, XOR, and NAND logic gates were realized based on all-optical tunable on-chip plasmon-induced transparency in plasmonic circuits. A large nonlinear enhancement was achieved with an organic composite cover layer based on the resonant excitation-enhancing nonlinearity effect, slow light effect, and field confinement effect provided by the plasmonic nanocavity mode, which ensured a low excitation power of 200 μW that is three orders of magnitude lower than the values in previous reports. A feature size below 600 nm was achieved, which is a one order of magnitude lower compared to previous reports. The contrast ratio between the output logic states “1” and “0” reached 29 dB, which is among the highest values reported to date. Our results not only provide an on-chip platform for the study of nonlinear and quantum optics but also open up the possibility for the realization of nanophotonic processing chips based on nonlinear plasmonics.

Multicast contention resolution based on time-frequency joint scheduling in elastic optical switching networks

Resolving the optical multicast contention in optical switch node is an effective approach to improve the performance of elastic optical multicast switch. An optical node architecture integrating with output shared all-optical Orthogonal Frequency Division Multiplexing (OFDM) network coding technology and shared feedback fiber delay lines (FDLs) buffer is designed. And a time-frequency joint scheduling strategy (TFJSS) is proposed. In TFJSS, the maximal weighted independent set algorithm is used to select the output packets with no overlapping spectrum among the contending multicast packets. The remaining contention packets are compressed by OFDM network coding with all-optical XOR operation. Hence, the contention is avoided in spectrum domain by encoding the contending unicast/multicast packets and changing the carrier frequency of encoded packets. If the network coding cannot successfully resolve the contending packets, the shared feedback FDLs are called to address the contention in time domain. Compared with the existing node architecture and scheduling algorithm, the simulation results show that the proposed architecture and the TFJSS can reduce the packet loss probability with low delay largely.

Digital Optical Physical-Layer Network Coding for mm-Wave Radio-Over-Fiber Signals in Fiber-Wireless Networks

We demonstrate a digital Optical Physical-layer Network Coding (OPNC) for mm-wave fiber-wireless signals modulated with up to 2.5 Gb/s On/OFF Keyed (OOK) data. The proposed OPNC concept uses an all-optical XOR gate comprising a Semiconductor Optical Amplifier-Mach Zehnder Interferometer (SOA-MZI) with SOAs being driven at low moderate electrical currents in order to perform the all-optical encoding between the OOK envelopes of the data, ignoring the high-frequency Sub-Carrier (SC) signal. In this scheme, network coding is performed on-the-fly at the central office and the resultant packet is broadcasted at the client nodes, where the decoding takes place. We demonstrate experimental results of OPNC using OOK data signals modulated on a 10 GHz SC with the aid of a second all-optical XOR gate for the decoding process at the client's site, reporting error-free performance for both synchronous/asynchronous data packets. The scenario of all optical encoding for 60 GHz SC frequencies followed by electrical decoding at the end-users is evaluated via PHY-layer simulations. Going a step further and considering the network level, we present a performance improvement on the network throughput by using the proposed network coding.

Dispersion on all-optical logic XOR gate using semiconductor optical amplifier

The effect of dispersion on an all-optical logic XOR gate is simulated and investigated. This Boolean function is realized by using semiconductor optical amplifiers-based Mach–Zehnder interferometer (SOAs-MZI). The dependence of the output quality factor (Q-factor) on input pulse energy, pulse width, SOA’s carrier lifetime, linewidth enhancement factor (α-factor) and saturation power has been examined and assessed. The obtained results confirm that the XOR gate implemented with the proposed scheme is capable of operating at a data rate of 80 Gb/s with logical correctness and high output Q-factor.

Simulation of soliton all-optical logic XOR gate with semiconductor optical amplifier

In this new study, a soliton all-optical logic XOR gate is numerically simulated and investigated. This Boolean function is realized by using a semiconductor optical amplifier (SOA)-assisted Mach–Zehnder interferometer. The dependence of the output quality factor (Q-factor) on the soliton characteristics and SOA’s parameters has been examined and assessed. The obtained results confirm that the soliton XOR gate implemented with the proposed scheme is capable of operating at a data rate of 80 Gb/s with logical correctness and high output Q-factor.

Ultrafast surface plasmon-polariton logic gates and half-adder.

In this paper, we present a plasmonic model system for the realization of ultrafast all-optical NOT, AND, OR, and XOR gate operations using linear interference effects in dielectric crossed waveguide structures. The waveguides for the surface plasmon-polaritons are produced by a simple but highly accurate microscopic lithographic process and are optimized for single mode operation at an excitation laser wavelength of 800 nm. The functionality of the presented structures is demonstrated using sub-30 fs laser pulses from a mode locked titanium:sapphire laser. Using leakage radiation microscopy we show ultrafast SPP switching and logic operations of one basic structure consisting of two crossed waveguides with an additional output waveguide along the bisecting line of the input waveguides. The individual gates are realized on a footprint of 10 µm × 20 µm. Experimental investigations are supported by finite-difference time-domain simulations, where good agreement between experimental results and numerical simulations is obtained. To exploit the high precision of the fabrication method and its huge potential for realizing functional complex plasmonic circuitry we experimentally demonstrate a half-adder structure and its operation by combining and cascading several plasmonic waveguide components and logic gate elements on an area of only 10 µm × 28 µm.

All-optical XOR and OR logic gates based on line and point defects in 2-D photonic crystal

In this paper, we have proposed an all-optical logic gate structure based on line and point defects created in the two dimensional square lattice of silicon rods in air photonic crystals (PhCs). Line defects are embedded in the ГX and ГZ directions of the momentum space. The device has two input and two output ports. It has been shown analytically whether the initial phase difference between the two input beams is π/2, they interfere together constructively or destructively to realize the logical functions. The simulation results show that the device can acts as a XOR and an OR logic gate. It is applicable in the frequency range of 0–0.45 (a/λ), however we set it at (a/λ=) 0.419 for low dispersion condition, correspondingly the lambda is equal to 1.55µm. The maximum delay time to response to the input signals is about 0.4ps, hence the speed of the device is about 2.5THz. Also 6.767dB is the maximum contrast ratio of the device.