Optical Half Subtractor Research Articles

All optical half subtractor based on threshold switching and beams interference mechanisms

Abstract In this paper, ultra-fast, compact and high contrast ratio all optical half subtractor based on photonic crystal designed and simulated. The proposed design will be constructed using both threshold switching and interference of beams mechanisms. The proposed structure is composed of six waveguides and a nonlinear ring resonator. The simulation results show that the contrast ratio for D and B ports were obtained about 18.80 and 15.05 dB, respectively. Also the maximum rise, fall and steady-state times and total footprint for suggested all optical half subtractor are 0.5, 0.25, 1.5 ps and 234 μm2, respectively.

Ultra-compact all-optical logical circuits for photonic integrated circuits

In this paper, a photonic crystal based ultra-compact Optical XOR gate followed by an optical half-subtractor is proposed. Plane wave expansion is used to evaluate the photonic bandgap of the devised structure. The output and efficiency of logical circuits can be improved by maintaining distinct thresholds for the output logic states, thereby enabling the design to operate even in low power inputs. Reliability of the structure is enhanced by retaining a threshold for the output value. The performance of the proposed circuit is examined using the Finite Difference Time Domain method. The output is considered as logic 1 when the power level exceeds 0.7 μW and logic ‘0’ if it is below 0.35 μW. The proposed logical circuit has high contrast ratio. The XOR gate has a contrast ratio of about 12.55 dB, and the half subtractor has 7.78 dB and 11.76 dB for Difference and Borrow respectively. These devices work at 1550 nm wavelength and are ultra-compact in size. The proposed structure of logic gates will be suitable for photonic integrated circuits due to its ultra-small and simple design.

Design and analysis of cross phase modulation based all optical half subtractor using carrier reservoir semiconductor optical amplifier

Design and analysis of cross phase modulation based all optical half subtractor using carrier reservoir semiconductor optical amplifier

All optical half-adder/subtractor using photonic-crystal-based nonlinear cavities.

In this paper, we aim to design a compact structure that can work both as an optical adder and subtractor. Also, as far as we know, one of the main disadvantages of previous optical adders or subtractors is that, inside a single structure, the levels of optical intensity for logic 1 at different output ports are different. In this work, we aim to solve this issue, too. For this purpose, two separate structures were designed for the half-adder and half-subtractor. The final structure was realized by combining these structures and adding an extra control port. When the control port is 0, the structure can work as an optical half-adder; however, when the control port is 1, the proposed structure can work as an all optical half-subtractor. The simulation results show that the rise time and ON/OFF contrast ratio are about 1.5 ps and 18.3 dB, respectively. Also the simulation results prove that the output levels for logic at all the output ports are at similar levels.

Implementation of optical Half-Subtractor using micro ring resonator loaded Mach–Zehnder structure

In this paper, we have proposed to simulate a novel optical half-subtractor using two micro ring resonator loaded in a Mach zehnder look like structure. We have shown that two microring resonator (MRR1 and MRR2) are placed parallel with each other to perform the half- subtractor operation and a phase shifter to changes the effective refractive index of light to adjust its phase. The proposed structure is entirely optical circuit and operates only on light signals. Hence, we can say that this paper describes the theoretical aspects for the implementation of optical half-subtractor using microring resonator. The mentioned circuit can be used in the field of optical computing and the communications systems.

All optical half subtractor based on linear photonic crystals and phase shift keying technique

Abstract In this work, the authors investigate the new structure of all optical half subtractor in a two dimensional photonic crystal based on wave interference and phase shift keying technique. The suggested structure is designed using 10 optical waveguides and one defect in the basic structure. The numeral methods such as plane wave expansion and finite difference time domain are used to analyze the proposed structure. According to obtained results, the rise and fall times, the working bit rate, the minimum and maximum values of the normalized power at ON and OFF states for output ports are 0.1 ps, 0.05 ps, 5 Tbit/s, 77 and 17%, respectively. According to results, high switching speed, compactness, low power consumption and ultra-fast operation are the main advantages of designed optical half subtractor compared with the previous structures.

A novel proposal for ultra-fast all optical half subtractor based on nonlinear ring resonators

Optical half subtractors are required for designing any optical computation system. Operation speed and the on/off contrast ratios are very important characteristics for any optical logic device. A novel structure composed of three nonlinear ring resonators and some optical waveguides are used for designing for the proposed half subtractor with improved operation speed and on/off contrast ratio. The simulation results show that the rise time for this structure is 1.5 ps. Also the on/off contrast ratios for B and D are 13.7 dB and 14.5 dB respectively.

A novel design of all optical half-subtractor using a square lattice photonic crystals

In this research, an all-optical half-subtractor is designed and simulated using two-dimensional photonic crystals. First, a photonic crystal structure is created using Si rods in the air context to obtain the optical half-subtractor. Afterward, using point and line defects, two waveguides are created for the input and two waveguides are created for the outputs. A high logical value and a low logical value are defined based on the optical power in each port. The FDTD method is used in the simulation of light propagation in the structure. The simulation results show that the designed half-subtractor has high optical power values for logic “1” and low values for logic “0”. The small size of the designed structure is among the advantages of this structure. Moreover, given that this half-subtractor is devoid of ring resonators, it can be used in high-speed integrated optical circuits. Another advantage of the proposed half-subtractor is that the optical powers in the outputs are similar in the high and low optical states.

Design and analysis of all optical half subtractor in 2D photonic crystal platform

In this paper, a novel all optical half subtractor based on threshold switching mechanism was proposed which has one bias port, two input ports and two output ports. The proposed design will be realized by three nonlinear resonant rings and eight waveguides. To analyze and simulate the proposed structure, we employed plane wave expansion (PWE) and finite difference time domain (FDTD) methods. Based on the comparison results, low power consumption, compactness, ultra-fast operation and high contrast ratio are the main advantages of designed all optical half subtractor compared with the previous structures. The ON-OFF contrast ratios for output ports (D and B ports) are about 10.31 dB and 14.96 dB, respectively. Also, the maximum rise, fall and delay times of the proposed structure are about 0.8 ps, 0.45 ps and 1.3 ps, respectively.

An all-optical half subtractor based on Kerr effect and photonic crystals

Optical half subtractor is one of the optical logic gates, which is very important for realizing all optical computing systems. The aim of this paper is to design a new structure for realizing an all-optical half subtractor based on photonic crystal nonlinear ring resonators. For this purpose, three nonlinear ring resonators are combined with the some optical waveguides to create the desired structure. A finite difference time domain method will be utilized to analyze and simulate the proposed structure. The simulation results show that the contrast ratio for D and B ports are 6.81 dB and 7.78 dB respectively. Moreover, the maximum rise and fall times for the proposed structure are 1.5 ps and 1 ps respectively.

Simple and compact optical half-subtractor based on photonic crystal resonant cavities in silicon rods.

We propose a very simple and compact structure to realize the subtracting operation using resonant cavities in a photonic crystal structure. The cross section of the structure is ${103}\;\unicode{x00B5}{\rm m}^2$103µm2 and is desirable for integration based on popular planar technology. In the designed subtractor, the cavity was responsible for selecting the wavelength. By changing the boundary rods' cavity condition, the mode could resonate at the desired frequencies. To have resonant cavities, we introduce four defect rods between the input and the output waveguides. The results exhibit the true performance of the device. We used only silicon rods in the proposed device, and hence it is very simple to be fabricated. The finite-difference time-domain method was used for analyzing the proposed structure. The simulation results show that the contrast ratio of the device is 5 dB. The maximum rise and fall times are 1.5 and 0.5 ps, respectively.

A novel proposal for all optical half-subtractor based on photonic crystals

Optical logic devices are the inevitable need for the future all optical computing and data processing. In this paper we are going to design and propose an all optical half subtractor using photonic crystal structure. The proposed structure will be realized using both threshold switching and beam interference. Finite difference time domain method used for analyzing the proposed structure. The simulation results show that the contrast ratio for D and B ports are 8 dB and 12 dB respectively. Also the maximum the maximum rise and fall times are 1 ps and 0.6 ps respectively.

All optical half subtractor using photonic crystal based nonlinear ring resonators

All optical subtractors are one of the optical digital devices that will play crucial roles in the next generation all optical data processing. In this paper we used three nonlinear photonic crystal based ring resonators for designing a novel structure for realizing all optical half subtractor. In the proposed structure X and Y are the input ports and D and B are the output ports. D is on when one of the input ports is ON and the other is OFF, however B is ON only when X is ON and Y is OFF. The maximum rise times for D and B are 2 ps and 3 ps respectively. Also the maximum fall times for D and B both are about 1 ps.

All-optical half-subtractor with low-time delay based on two-dimensional photonic crystals

In order to rapidly process information, high-speed processors are required. Optical instruments are appropriate for optical processors because of the high speed of information transference. In order to design optical processors, a structure that has the ability to integrate is required. Photonic crystals are suitable structures that can be used to design and implement different kinds of optical instruments. In this paper, an optical half-subtractor has been designed, based on two-dimensional photonic crystals. Owing to its small size and simple design, this half-subtractor can be used in optical integrated circuits. The very low-time delay of this half-subtractor is responsible for its high bit-rate.