Reconfigurable All-optical Logic Research Articles

Simple and reconfigurable all-optical logic gate

A photonics-based digital signal processing structure that has the ability to realise all the six basic logical operations, namely XOR, OR, AND, XNOR, NOR and NAND, is presented. It is based on applying the two digital inputs into a dual-polarisation modulator and adjusting the angle of a waveplate connected to the modulator output to realise different logical operations. The proposed dual-polarisation modulator based optical logic gate has a simple and compact structure and robust performance. Switching between different logical operations can be realised in high speed by adjusting only one system parameter, with no change in the system physical configuration. The proposed dual-polarisation modulator based optical logic gate is theoretically analysed. Using the system parameter setting obtained from the theoretical analysis, the six basic logical operations are experimentally demonstrated. To our knowledge, this is the first report of an optical logic gate that is capable of switching between all the six basic logical operations by adjusting only one system parameter.

Reconfigurable all-optical logic device based on cross-phase modulation across highly non-linear fiber

All-optical logic gates are the basic building blocks of photonic integrated circuits to be used for signal processing, to ensure high speed signal processing and decreasing complexity of network. In this paper, reconfigurable all-optical logic gate has been proposed and numerical simulations are analysed at a bit rate of 120 Gb/s. Wavelength Converter, NOT, NOR, AND, XOR, XNOR, A¯.B and OR are the all-optical logic gates that has been designed and implemented using single circuit and has minimum quality factor of 27 dB. All the signal processing operations have been implemented by the exploitation of cross-phase modulation in two parallelly placed (Mach-Zehnder Interferometric configuration) highly nonlinear fibers (HNLF). The influence of variation in input power, at different length of HNLF determines that the quality factor increases for increase in power or length of highly nonlinear fiber up to a certain limit. Quality factor increases for decrease in effective area of the highly nonlinear fiber for a certain range of input power and saturates for further increase in input power. Also, the quality factor is not directly affected with increase in bit rate but adversely affected by increase in dispersion.

Compact and High-Speed All-Optical 2n:1 Multiplexer Scheme Using MRRs

The purpose of this research paper is to present a new all-optical scheme to implement the logical behavior of generalized [Formula: see text]th-order (2[Formula: see text]:1) multiplexer logic. The proposed all-optical design is based on micro-ring resonator (MRR)-based all-optical switches and constructed by using “2[Formula: see text]-2” MRR structures, arranged in a series “[Formula: see text]” stage architecture. The presented configuration enjoys advantageous features like compact-sized systematic structure and ultra-fast speed. To validate the logical behavior of the proposed [Formula: see text]th-order multiplexer, a second-order (22:1) multiplexer is derived (from the proposed scheme) and discussed. Further, the usability of the presented all-optical multiplexer is demonstrated by developing an all-optical reconfigurable logic gate that can be reconfigured to perform various logic operations. To verify the logical behavior of MRR-based all-optical switch and presented all-optical multiplexer logic, numerical simulations through MATLAB software have been performed. The reported reconfigurable logic structure is also simulated in the MATLAB environment to validate the desired behavior.

The design of a reconfigurable all-optical logic device based on cross-phase modulation in a highly nonlinear fiber

A simple reconfigurable ultrahigh-speed optical device which can be configured to optical NOT, AND, or XOR logic operation via slight variations in the input signals applied to two identical parallel highly nonlinear fibers (HNLFs) is described. The cross-phase modulation (XPM) in the HNLF and phase shifter are used in the design to realize a reconfigurable all-optical logic gate operating at 120 Gb/s. The proposed reconfigurable ultrahigh-speed all-optical logic device could play a crucial role in the realization of future all-optical high-performance flexible optical networks.

Performance analysis of optical micro-ring resonator as all-optical reconfigurable logic and multiplexer in Z-domain

Performance and design methodology of [Formula: see text] multiplexer (MUX) and all-optical reconfigurable logic circuit using GaAs–AlGaAs-based optical micro-ring resonator (OMRR) are presented in current paper. Proposed design of reconfigurable logic circuit is capable to perform eight different logic operations. Performances of the logic circuits have been theoretically analyzed using Z-domain modeling. Numerical simulation results confirming the method are explained in the present paper. Proposed circuit is simple, compact, efficient as it have minimum number of OMRR, low operating power, high operating speed and high Q-factor. Different ‘figure of merits’ of the purposed model are calculated from the simulation results.

Micro-ring resonator based all-optical reconfigurable logic operations

An all-optical reconfigurable logic operation essentially constitutes a key technology for performing various processing tasks with ultrafast signal-processing technologies. We present designs and simulations for highly cascadable all-optical reconfigurable logic operations using GaAs–AlGaAs micro-ring resonator based optical switches and multiplexers. The switching action of the ring resonator is achieved through variation in the refractive index of the ring resonator produced by the two-photon absorption (TPA) effect through the application of optical pump pulse. The proposed circuit can perform any of the four digital logic operations (NOT, NOR, XOR, AND) by using the appropriate optical pump signal at the selection port of the multiplexer. We have tried to exploit the advantages of micro-ring resonator based all optical switch to design an all-optical circuit. The reconfigurable nature of the circuit offers maximum flexibility for the end user since the entire application can be changed simply by adjusting the multiplexer select line signals. Numerical simulation confirming described methods is given in this paper.

Ultrahigh Speed Reconfigurable Logic Operations Based on Single Semiconductor Optical Amplifier

We demonstrate an optical gate architecture using a single SOA to perform AND, OR and NOT logic functions. Simple reconfigurable all-optical logic operations are implemented using RZ modulated signals at 40 Gb/s. Contrast ratio and extinction ratio values have been analysed for the different types of logic gates. Maximum extinction ratio and contrast ratio achieved are 19dB and 17.2 dB respectively. Simple structure and potential for integration makes this architecture an interesting approach in photonic computing and optical signal processing.

Design of All-Optical Reconfigurable Logic Unit With Bacteriorhodopsin Protein Coated Microcavity Switches

We present a theoretical design of an all-optical reconfigurable logic unit based on optically controlled microcavity switches, for realization of all-optical computing circuits. It can execute different logic and arithmetic operations such as half and full adder or subtractor, by only changing the control inputs on the same circuit. Theoretical designs considering bacteriorhodopsin (BR) protein coated microcavities in tree architecture have been presented. The combined advantages of high Q-factor, tunability, compactness, switching of near-IR signals at telecom wavelengths (1310/1550 nm) with low-power control signals, and flexibility of cascading switches to form circuits, makes the designs promising for practical applications. They combine the ultrahigh sensitivity of both BR and microresonators to define a novel paradigm of all-optical computing based on hybrid nanobiophotonic integration.

基于单个半导体光放大器的非线性偏振旋转效应实现全光可重构多逻辑门

We demonstrate an all-optical reconfigurable logic gate based on dominant nonlinear polarization rotation accompanied with cross-gain modulation effect in a single semiconductor optical amplifier (SOA). Five logic functions, including NOT, OR, NOR, AND, and NAND, are realized using 10-Gb/s on-off keying signals with flexible wavelength tunability. The operation principle is explained in detail. By adjusting polarization controllers, multiple logic functions corresponding to different input polarization states are separately achieved using a single SOA with high flexibility.

All-optical reconfigurable logic operations with the help of terahertz optical asymmetric demultiplexer

An all-optical reconfigurable logic operation essentially constitutes a key technology for avoiding complex and speed limited optoelectronics conversions and performing various processing tasks. All-optical reconfigurable logic operations with the help of terahertz optical asymmetric demultiplexer (TOAD) is proposed and described. The paper describes the all-optical reconfigurable logic operations using a set of all-optical multiplexer and optical switches. We have tried to exploit the advantages of TOAD-based switch to design an integrated all-optical circuit which can perform the different logic operations AND, XOR, NOR and NOT. Numerical simulation confirming described methods is given in this paper.

Reconfigurable all-optical logic gate using four-wave mixing (FWM) in HNLF for NRZ-PolSK signal

We demonstrate a reconfigurable all-optical logic gate for NRZ-PolSK signal based on FWM in a highly nonlinear fiber at 10 Gb/s. Half subtracter, XOR, AB̄, Ā B or XNOR, AND, and NOR logic gates can be implemented simultaneously. The input power for the HNLF is optimized to be as low as about 15.2 dBm and the high Q factors above 8 dB for eye diagrams are achieved. Experimental results show Q factors of AB̄, Ā B, AND, and NOR were higher than those of XOR, and XNOR. Error-free operation is achieved experimentally for 10 Gb/s 2 7–1 pseudorandom bit sequence (PRBS) data. Power penalties for the logic gate are less than 3 dB. Simulation analysis about the wavelength characteristic for all logic gates is given and it predicts that the reconfigurable logic gate can realize error-free operation when the wavelength separation is less than 5 nm.

Reconfigurable All-Optical Logic Gates for Multi-Input Differential Phase-Shift Keying Signals: Design and Experiments

Differential phase-shift keying (DPSK) signals are promising candidate for the long-haul transmission systems. However, the development of the all-optical signal processing techniques for the DPSK signals is still in its infancy, especially the all-optical logic operations. In this work, a general scheme for reconfigurable logic gates for multi-input DPSK signals with integration possibility is proposed. Benefiting from the optical logic minterms developed by two kinds of optical devices, i.e., optical delay interferometers and semiconductor optical amplifiers (SOAs), target logic functions can be realized by combining specific minterms together. The scheme is reconfigured by changing the phase control of the delay interferometers or the input wavelengths. The latter approach was adopted in the experimental trials. Although the outputs of the scheme are on-off keying (OOK) signals, the data format is compatible with all-optical decision circuits where OOK format is preferred. Two- and three-input experiments are carried out at 20 Gbit/s with nonreturn-to-zero DPSK signals. Various logic operations are demonstrated, including full sets of two- and three-input minterms, AND, NOR, XOR, and XNOR logic operations where the AND and NOR logic are derived simultaneously and the XOR and XNOR logic are convertible. The optical SNR as well as the Q-factor of the two- and three-input results are measured and compared. It shows that the input powers to the SOAs are critical in achieving good extinction ratio and the Q-factor of logic results degrades when several minterms are combined. The recovery time of the SOAs need to be optimized as well. Finally, the scaling issues of the scheme are discussed.

利用单个半导体光放大器实现非反转归零码的可重构全光逻辑门

利用单个半导体光放大器实现非反转归零码的可重构全光逻辑门

Operation properties of a reconfigurable photonic logic gate based on cross phase modulation in highly nonlinear fibers

The operation features of a 160 Gb / s reconfigurable all-optical logic gate based on cross phase modulation in highly nonlinear fibers are numerically investigated for six logic functions (XOR, OR, NAND, NOR, NOT, and AND). High bit rate operation is numerically demonstrated for a wide input signal wavelength range ( > 20 nm ). Performance enhancement of the proposed setup operating at 160 Gb / s for different signal wavelengths is exhibited by using a 2R regenerator based on the self-phase modulation effect in highly nonlinear fibers at the gate's output. The operation of the multi-functional logic gate is investigated considering either a pulsed or a continuous wave probe.

Ultrafast All-Optical Signal Processing Based on Single Semiconductor Optical Amplifier and Optical Filtering

<para xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink"> We propose and demonstrate several all-optical signal-processing technologies, including wavelength conversion (WC), leading/trailing edge detection, and logic gates based on a semiconductor optical amplifier (SOA) and a detuning optical bandpass filter (OBF). The system is based on pump-probe scheme. When the pump signal is return-to-zero (RZ) format, both inverted WC and noninverted WC at 40 Gb/s are obtained, and the polarity variation is highly dependent on the OBF detuning. When the pump signal is nonreturn-to-zero (NRZ) format, both the inverted WC and leading/trailing edge detection are obtained. In the inverted WC, the OBF detuning is small, and it helps to accelerate the amplitude recovery. However, in the noninverted WC and pulse edge detection, the OBF detuning is relatively large, and it acts as frequency–amplitude conversion. Finally, we present all-optical reconfigurable logic gates based on various nonlinearities in an SOA. The logic gates including <emphasis emphasistype="smcaps">and</emphasis>, <emphasis emphasistype="smcaps">nor</emphasis>/<emphasis emphasistype="smcaps">not</emphasis>, and <emphasis emphasistype="smcaps">or</emphasis> are obtained by four-wave mixing, cross-gain modulation, and transient cross-phase modulation in the SOA, respectively. The <emphasis emphasistype="smcaps">nor</emphasis> and <emphasis emphasistype="smcaps">or</emphasis> gates are capable of operating at 40 Gb/s with the help of the OBF detuning. The <emphasis emphasistype="smcaps">xnor</emphasis> gate is implemented by combining the <emphasis emphasistype="smcaps">and</emphasis> output and <emphasis emphasistype="smcaps">nor</emphasis> output. </para>

Numerical Investigation of a 160-Gb/s Reconfigurable Photonic Logic Gate Based on Cross-Phase Modulation in Fibers

A simple reconfigurable all-optical logic gate based on cross-phase modulation in highly nonlinear fibers is numerically demonstrated. Fine performance at 160 Gb/s is obtained for five logic functions (xor, or, nand, nor and not). The implementation simplicity and the high-bit-rate operation make the proposed device suitable for ultrafast applications in the emerging all-optical networks

Ultrahigh-speed reconfigurable logic gates based on four-wave mixing in a semiconductor optical amplifier

We have demonstrated simple reconfigurable all-optical logic operations based on four-wave mixing in semiconductor optical amplifier and encoding information in the polarization of the input signals. Experimental implementation of six logic functions (including XOR, XNOR, AND, NOR, etc.) operating at 10 Gb/s were realized by simply adjusting two polarization controllers in the setup.

Regenerative and reconfigurable all-optical logic gates for ultra-fast applications

All-optical ultra-fast and reconfigurable logic gates have been implemented exploiting simple and low-cost schemes based on nonlinear optical loop mirrors. Regenerative properties of the realised optical logic gates have been demonstrated.