Execution of all-optical Boolean OR logic using carrier reservoir semiconductor optical amplifier-assisted delayed interferometer

In this article, the acceleration attained in gain recovery dynamics of travelling-wave-type semiconductor optical amplifier (SOA) at the expense of structural optimization is illustrated via numerical simulations. A pump–probe scheme has been utilized in order to study the outcomes of optimization of SOA operational and structural parameters on its effective gain recovery time ( $${\tau _\mathrm{e}}$$ ). A set of optimized SOA parameters are formulated from gain recovery dynamics studies after keeping practical implementation considerations in vision. Further, the impacts of altering SOA structural and operational parameters such as injection current (I), amplifier length (L), active region width (w), active region thickness (t) and optical confinement factor ( $${\varGamma } $$ ) on gain recovery time improvement achieved are further investigated on the performance of a cross-gain modulation (XGM) in SOA-based all-optical half-subtracter in terms of two designated performance metrics: quality factor (Q-factor) and extinction ratio (ER). It has been revealed that reduced gain recovery time-optimized SOAs-based all-optical half-subtracter arranged in a co-propagating manner exhibits improved Q-factor and ER (dB) performance at high bit rates of operation ( $$\le $$ 80 Gbps).

In this article, two structures are proposed for all-optical AND, XOR, and OR logic gates based on nonlinear photonic crystals. The proposed structures include a Y-junction and ring resonator-based limiters. Two different structures are designed as the limiter in order to produce AND–XOR and AND–OR logic gates. Nonlinear rods of proposed structure have been used in order to create the frequency shift for different values of input power. Finite difference time domain method has been utilized to simulate the performance of proposed logic gates. Simulation results show that the smallest ON–OFF logic-level contrast ratio for the structures proposed for AND–XOR and AND–OR logic gates are 20.29 dB and 16.7 dB, respectively.

Recently M. Morris Mano presented a method for performing Boolean OR, AND and NOT operations by means of arithmetic and conditional transfer operations in a decimal computer lacking builtin logical instructions [1]. When A , B , C are variables whose defined value is 0 or 1 and a , b , c are the corresponding integer variables with values 0 or 1, his Boolean OR was defined by: “The result of an OR operation of Boolean variables is the same as the arithmetic addition of the a , b , c integer variables after which the following test is made: (a) If the sum is equal to zero, the result is correct; (b) If the sum is larger than zero, the answer is 1.”

A recently reported theory of gain recovery in semiconductor optical amplifiers (SOAs) is extended to develop approximate expressions for the gain compression and recovery time in terms of probe wavelength, unsaturated gain and device length. These results indicate (1) that the gain recovery time should be approximately inversely proportional to the transmission gain spectrum, and (2) that the wavelength dependence of the gain compression caused by the pump pulse will be dominated by the spectrum of the SOA gain at the probe wavelength. These predictions are tested against pump-probe measurements of gain compression and recovery in a series of four semiconductor optical amplifiers of different lengths but otherwise identical structures. A continuous wave probe beam from a tunable laser is used to measure the wavelength dependence of gain compression and recovery times. Spectral features are used to verify the correlations between these quantities and their dependence on device length.

Background and Objectives: Recently, photonic crystals have been considered as the basic structures for the realization of various optical devices for high speed optical communication.Methods: In this research, two dimensional photonic crystals are used for designing all optical logic gates. A photonic crystal structure with a triangular lattice is proposed for making NAND, XNOR, and OR optical logic gates. Using the structure as the intended logic gate is possible without the need to change the structure through the use of the phase difference at the inputs. Line and point defects have been used to propagate light from inputs to output. The logical values "0" and "1", are defined based on the amount of transferred optical power to the output.Results: The simple structure and the use of line and point defects, instead of ring resonators, reduce the complexity of the design and its use in optical logic integrated circuits. Another advantage of proposed structure, in comparison to the previous structures is the reduction in delay time that increases its speed. The maximum delay time of the proposed optical NAND, XNOR, and OR gates is about 0.1ps.Conclusion: In this study, one structure is suggested for realizing NAND, XNOR, and OR logic gates. This structure has a small size and low delay time, and is suitable for use in optical integrated circuits.

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

The NLO properties of organic materials have been studied with the single-beam Z-scan technique using a CW laser beam. A He–Ne laser operated at 632.8 nm with a power output of 12 mW is used for this study. A closed-aperture setup is used to measure the nonlinear refractive index of Patent blue V dye dissolved in distilled water. The material exhibits negative nonlinearity. Optical limiting behavior has been observed for this dye. Further, we have modified the Z-scan setup suitably to realize all-optical AND and OR logic gates.

Precision and grade are two important quantitative indexes. The purpose of this paper is to combine precision and grade, and explore new extended rough set model. Based on logical OR operation of precision and grade, this paper proposes model of logical OR operation of variable precision lower approximation operator and grade upper approximation operator. In the new model, fundamental structure and properties are obtained by transformation formulas between variable precision approximations and graded approximations, furthermore regular algorithm and structural algorithm are proposed and analyzed. Finally a practical example is given to illustrate the model and the algorithms. The new model has extended variable precision rough set model, graded rough set model and classical rough set model, and so these models have obtained similar properties of approximation operators.

A study of the transient response of semiconductor optical amplifiers (SOAs) is presented. The gain saturation and recovery times, as well as the pulse distortion due to the cross-gain modulation produced by the bias current and input signal power variations have been evaluated for different scenarios. Observations of the temporal variation of the rate carrier density at the input and output of the amplifier show the effects on gain saturation for different input powers. Gain saturation and saturation-induced inter- channel crosstalk are evaluated. The results show that fast gain dynamic in SOAs. Transient effects of gain saturation and recovery times occur on a time scale of between 500 ps and 1 ns. It is concluded that SOAs are sensible to channel crosstalk in WDM systems operating at high bit rates.© (2001) COPYRIGHT SPIE--The International Society for Optical Engineering. Downloading of the abstract is permitted for personal use only.

S.1071-1074

Bioinspired artificial ionic components are extensively utilized to mimic biological systems, as the vast majority of biological signaling is mediated by ions and molecules. Particular attention is given to nanoscale fluidic components where the ion transport can be regulated by the induced ion permselectivity. As a step from fundamentals toward ion-controlled devices, this study presents the use of ionic diodes made of oppositely charged polyelectrolytes, as a gate for low-abundance molecules. The use of ionic diodes that exhibited nonlinear current-voltage responses enabled realization of a basic Boolean operation of an ionic OR logic gate. Aside from the electrical response, the asymmetric ion transport through the diode was shown to affect the transport of low-abundance molecules across the diode, only allowing crossing when the diode was forward-biased. Integration of multiple diodes enabled implementation of an OR logic operation on both the voltage and the molecule transport, while obtaining electrical and optical output readouts that were associated with low and high logic levels. Similarly to electronics, implementation of logic gates opens up new functionalities of on-chip ionic computation via integrated circuits consisting of multiple basic logic gates.

This paper is to construct new operation of approximation operators, and explore its calculation. First it proposes logical OR operation of variable precision upper approximation operator and grade lower approximation operator. Then regular algorithm and structural algorithm are proposed and analyzed, and furthermore it obtains an important conclusion that structural algorithm has advantages in space complexity. Finally the new operation and its algorithms are explained by a medical example.

Besides storage information, memristor can also be used in logic operation. Although IMPLY and CLEAR based on memristor are logic completeness, there would be more steps when representing AND and OR operation which are more commonly used. Based on this, the paper presents a feasible approach to implement OR logic, and implements OR logic in NOR memory array based on memristors. Utilizing the advantage of parallel computing, NOR memory array based on memristors can greatly improve the speed of logic operation, and offering a new method for the combination of storage and operation.

100 Gb/s all-optical multifunctional AND, NOR, XOR, OR, XNOR, and NAND logic gates in a single compact scheme based on semiconductor optical amplifiers

Gain recovery dynamics are studied in electrically pumped quantum dot (QD) based semiconductor optical amplifiers (SOAs) after amplification of double femtosecond laser pulses using ultrafast pump-probe spectroscopy with heterodyne detection. The authors observe a distinct change in gain recovery in the ground state when a significant excited state population is achieved. A complete gain recovery is found when two 150fs pulses with 5ps time delay pass through the SOA in resonance to the ground state under high injection currents of 80–100mA. The obtained results open the way for ultrafast (>200GHz) operation in p-doped QD based SOAs at 1.3μm telecommunications wavelengths.