All optical logic NAND gate based on two-photon absorption in semiconductor optical amplifiers

We propose a new scheme to realize all optical logic NAND operating at high speeds up to 250 Gb/s utilizing the ultrafast phase response during two-photon absorption (TPA) process in semiconductor optical amplifiers (SOA). NAND gate is important because other Boolean logic elements and circuits can be realized using NAND gates as basic building blocks. Rate equations for semiconductor optical amplifiers (for input data signals with high intensity) configured in the form of a Mach-Zehnder interferometer have been solved. The input intensities are high enough so that the two-photon induced phase change is larger than the regular gain induced phase change. The performance of this scheme is analyzed by calculating the quality factor of the resulting data streams. The results show that both AND and NAND operations at 250 Gb/s with good signal to noise ratio are feasible.     

Optoelectronic logic operations by triangular-barrier optoelectronic switch

Optoelectronic logic operations were successfully demonstrated by triangular-barrier optoelectronic switch (TOPS). TOPS has not only differential gain, bistable and latch characteristics simply by changing the bias voltages, but also high sensitivity and high gain. We first confirmed AND and OR operations using a single TOPS, and also realized NOT, NAND, NOR and XOR operations using dual TOPS without any optical or electrical reset signals. These logic operations by dual TOPS can be attained in the same electrical circuit configuration.     

Implementation of optical logic gates using closed packed 2D-photonic crystal structure

A proposal for implementation of optical logic gates using a two dimensional closed packed photonic crystal structure is presented here. The logic operations are realized by a control signal and the input signal(s) applied across two adjacent faces, while the output is obtained along one of the remaining faces. Finite Difference Time Domain simulations show that, this structure can be used to realize AND, OR, NOT, XNOR, NAND operations, if phase difference of π/2 is maintained between the control and the input signal. Further it is found that the same structure can be used as a switch, if Kerr nonlinearity is introduced to the dielectric rods constituting the photonic crystal structure.     

All-optical Serial Data Transfer between Registers using optical non-linear materials

The inherent parallelism of optical signal is an advantageous feature for high-speed computations and other digital logic operations. Different techniques have been proposed for performing arithmetic, algebraic and logic operations using light as the information-carrier. Here we propose a new method for Serial Data Transfer between Registers using optical non-linear material. This system is all-optical in nature. Optical NAND gate and NOT gate are the basic building blocks of this system.     

Simulation of two photon absorption in silicon wire waveguide for implementation of all optical logic gates

All optical switching action of silicon wire waveguide for the design of the proposed logic gates is simulated. This is one possible building block of the future all optical computer or photonic devices. All optical logic gates NOT, NAND and AND gates using two photon absorption in silicon wire waveguide are presented. Use of ultra short pulse has negligible free carrier absorption effect; hence the operating speed of the gates is very high and has potential application in photonic processing. NAND gate is universal one and thus one can perform any logical operation using this. The device (Si wire WG) requires low energy pulse and is ultrafast one.     

All optical switching in henna thin film

The optical nonlinearity in henna (Lawson (2- hydroxyl-1,4 naphthoquinone) film was utilized to demonstrate all optical switching. The nonlinear absorption of the henna film was calculated by measuring the transmission of the laser beam (λ = 488 nm) as a function of incident light intensities. The observed nonlinear absorption is attributed to a two-photon absorption process. The pump and probe technique was used to demonstrate all optical switching. The switching characteristics can be utilized to generate all-optical logic gates such as simple inverter switches (NOT) NOR, AND NAND logic functions.     

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.     

A method of optical implementation of frequency encoded all optical logic gates based on multiphoton processes in non linear material

A novel frequency encoded all optical logic gates are proposed exploiting multiphoton processes in non linear optical medium. In the frequency encoding of the information the ‘0’ is represented by a frequency ω and ‘1’ is represented by another frequency 2ω. The gates proposed are NOT, OR, AND, NAND and NOR among which NAND and NOR are universal. Using these gates one can generate other important gates and logical function generating all optical devices. Two main three-photon processes, second harmonic generation (SHG) and parametric light generation (PLG) are used to implement the gates and the corresponding appropriate non linear material is LiB₃O₅ (LBO) which has wide operating and transparency range in the wavelength 350–3,200 nm. The source of optical frequency encoded signal may be derived from an external cavity diode laser generating a wavelength 1,560 nm for ω (‘0’ state of information) and its second harmonic 780 nm for 2ω (‘1’ state of information).     

On the design of ultrafast all-optical NOT gate using quantum-dot semiconductor optical amplifier-based Mach–Zehnder interferometer

The feasibility of implementing an ultrafast NOT gate by means of a two-input Mach–Zehnder interferometer (MZI) that employs quantum-dot semiconductor optical amplifiers (QD-SOAs) is theoretically explored and shown. For this purpose a numerical treatment is conducted by modeling the propagation of strong pulses through a QD-SOA and the resultant change of the QD-SOA gain dynamics. This procedure allows to evaluate the impact of the critical parameters on the MZI complementary output port and find which is the most appropriate way to be selected and combined. The analysis of the simulation results reveals that with the non-data driven QD-SOA constantly held in the linear gain regime, the other QD-SOA, which is perturbed by the data to be logically inverted, must be operated in a nonlinear regime. This is defined by the drop of the specific QD-SOA gain by approximately 5.5 dB from its unsaturated value, which is caused by a data peak power being 4 dB higher than its saturation input power. Moreover, in order for the design to be complete, both QD-SOAs must be of medium length, provide a maximum modal gain such that their net gain exceeds by two orders of magnitude that at transparency, be biased at moderate current density and exhibit an electron relaxation time from the excited state to the ground state as fast as possible. Provided that these conditions are satisfied then a more than adequate extinction ratio can be obtained, which ensures that Boolean NOT logic is executed at 160 Gb/s both with logical correctness and high quality using QD-SOAs in a structurally simple, power efficient and operationally flexible version of the MZI.     

n-step optical simulation of the n-qubit state: Applications in optical computing

A method to implement optically 2ⁿ states in n steps, using n optical position bits, is presented. The implementation of the NOT and C-NOT operations, as well as the Fredkin-Toffoli and conditional sign change gates are also discussed.     

A novel frequency encoded all optical logic gates exploiting polarization insesensitive four wave mixing in semiconductor optical amplifier, filtering property of ADD/DROP multiplexer and non-linearity of reflective semiconductor amplifier

All optical logic gates exploiting polarization independent four wave mixing in semiconductor optical amplifier (SOA), filtering property of ADD/DROP multiplexer (ADM) and non-linearity in reflective semiconductor optical amplifier (RSOA) have been proposed. The logic gates proposed are polarization independent which ensures hardware simplicity and greater speed. The all optical frequency encoded logic gates NOT, OR, NOR, AND, NAND, X-OR, X-NOR are implemented which are very useful in optical computing ad signal processing, cryptography, etc. The logic gates proposed have the advantages that there is no intensity loss dependent problem, and are polarization and temperature insensitive.     

A method of implementation of frequency encoded all optical logic gates based on non-linear total reflectional switch at the interface

A novel method of implementation of frequency encoded logic gates NOT, OR, AND, NOR, NAND, X-OR, X-NOR is discussed. The frequency sources and physical requirements for the implementation are also discussed. The non-linear material (liquid) suitable for these operations to be performed should be of large non-linear coefficient, high reverse saturation absorption, large thermo-optic coefficient and low viscosity. The input controlling beams used to induce non-linearity in the switch are either of frequency υ₁ or υ₂ and the probe beam is a mixed signal of frequencies υ₁ and υ₂. Depending on the nature of the controlling inputs the output conditions of the probe can be adjusted to get different logic gates.     

All optical NOR and NAND gate based on nonlinear photonic crystal ring resonators

In this paper we proposed optical NOR and NAND gates. By combining nonlinear Kerr effect with photonic crystal ring resonators first we designed a structure, whose optical behavior can be controlled via input power intensity. The switching power threshold obtained for this structure equal to 2 kW/μm². For designing the proposed optical logic gates we employed two resonant rings with the same structures, both rings at the logic gates were designed such that their resonant wavelength be at λ = 1550 nm. Every proposed logic gate has one bias and two logic input ports. We used plane wave expansion and finite difference time domain methods for analyzing the proposed structures.     

n-step optical simulation of the n-qubit state: Applications in optical computing

A method to implement optically 2ⁿ states in n steps, using n optical position bits, is presented. The implementation of the NOT and C-NOT operations, as well as the Fredkin-Toffoli and conditional sign change gates are also discussed.     

Implementation of a novel hybrid encoding technique and realization of all optical logic gates exploiting difference frequency generation alone

A novel hybrid encoding technique scheme is proposed. Using this technique and difference frequency generation different all optical logic gates NOT, OR, AND, NAND, NOR, and X-OR are realized.     

Ultrasmall optical logic gates based on silicon periodic dielectric waveguides

An ultrasmall silicon periodic dielectric waveguides-based multimode interference all-optical logic gate has been proposed. The device consists of three 205 nm wide single-mode input waveguides, a 1.1 μm wide and 5.5 μm long multimode interference waveguide, and three 205 nm wide single-mode output waveguides. The total length and width of the device are 13.7 μm and 3.2 μm, respectively. By changing the states of the input optical signals and/or control signals launched into the device, multifunctional logic functions including OR, NAND, NOR, and NOT gates are performed, and each logic function can be realized at a specific output waveguide in accordance with the launched control signals. The ultrasmall multifunctional logic device has potential applications in high density photonic integrated circuits.     

Ultra high-speed optical signal processing based on single SOA at 60 Gb/s

The paper shows the design of all-optical logic gates OR, AND, NOT, NOR, XNOR, XOR at ultra high speed by using SOA. The simulations of all logic gates are obtained by XGM and FWM in SOA at 40 Gb/s and 60 Gb/s. The OR, AND, NOR logic between two data sources are obtained using a pump signal, while another logic XNOR using two data. The NOT, XOR obtained using FWM and XGM combined. Thus realization of these logics at 40 Gb/s and 60 Gb/s will lead revolution growth in optical signal processing for high-speed operation.     

Noise-free logic and Set-Reset latch operation in a triple-well potential system

We demonstrate additive driving force can induce logic and Set-Reset latch operation in a triple-well potential system and find the optimal parameter region with contour maps. The logic input signal plays the role of system bias. To be specific, the external driving force makes the system jump from high potential well to low potential well without jumping back, and thus can induce correct logic output. The problem that the optimal parameter region is too narrow can be solved in two ways: one is to increase the amplitude of the logic input signal, and the other is to introduce of logical vibration resonance. In addition, the logic input itself can be directly acted as the driving force to make the system in the correct potential well, that is, to achieve the correct logic and Set-Reset latch operation without other external driving force.     

All-optical NOT and XOR logic operation at 2.5 Gb／s based on semiconductor optical amplifier loop mirror

All-optical XOR and NOT logic operations based on semiconductor optical amplifier loop mirror (SLALOM) aresimultaneously demonstrated theoretically and experimentally. Based on a segmented semiconductor optical amplifier model, the all-optical logic operation process is simulated theoretically. In an experimental study, 2.5 Gb/s all-optical XOR operation was achieved in the output port of SLALOM, while all-optical NOT operation was achieved in the input port through a circulator at the same time.     

All-optical reconfigurable multi-logic gates based on nonlinear polarization rotation effect in a single SOA

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.