Ali Newaz Bahar

Extremely Low Loss of Photonic Crystal Fiber for Terahertz Wave Propagation in Optical Communication Applications

Abstract An enormously low loss symmetrical hybrid decagonal porous core spiral photonic crystal fiber (SH-PCF) has been proposed for terahertz (THz) wave guiding. The modal characteristics of the fiber and its mathematical analysis have been numerically completed using a full-vector finite element method (FEM). Simulation results show an ultra-low material loss of 0.0167 cm−1 and large effective area 1.95×106 µm2 which is 91.6u2006% of bulk absorption material loss at controlling frequency f=1.0 THz with a core porosity 42u2006%. Additionally, proposed structure establishes the comparatively higher core power fraction maintaining lower scattering loss about 1.8×10−15u2006dB/cm at the same operating frequency. It promises the aforementioned advantages for efficient THz wave propagation.

New modified-majority voter-based efficient QCA digital logic design

ABSTRACT Quantum-dot cellular automata (QCA) is an emerging nanotechnology and a possible alternative solution to the limitation of complementary metal oxide semiconductor (CMOS) technology. One of the most attractive fields in QCA is the implementation of configurable digital systems. This article presents a novel multifunctional gate called the modified-majority voter (MMV). The proposed gate works on the explicit interaction of the cell characteristic property for the implementation of digital circuits. This prominent feature of the proposed gate reduces the maximum hardware cost and implements highly efficient QCA structures. To verify the functionality of the proposed gate, some physical proofs, truth table and computational simulation results are performed. These results assured the validity of the existence of the proposed gate. It also dissipates less energy which has been calculated under three separate tunnelling energy levels using the QCAPro tool. To prove the effectiveness of the proposed MMV gate, several optimal irreversible arithmetic circuits such as three-input XOR, half-adder and full-adder are proposed. The modular layouts are verified with the freely available QCADesigner tool version 2.0.3.

An Architecture of 2-Dimensional 4-Dot 2-Electron QCA Full Adder and Subtractor with Energy Dissipation Study

Quantum-dot cellular automata (QCA) is the beginning of novel technology and is capable of an appropriate substitute for orthodox semiconductor transistor technology in the nanoscale extent. A competent adder and subtractor circuit can perform a substantial function in devising arithmetic circuits. The future age of digital techniques will exercise QCA as preferred nanotechnology. The QCA computational procedures will be simplified with an effective full adder and subtractor circuit. The deficiencies of variations and assembly still endure as a setback in QCA based outlines, and being capricious and inclined to error is the limitation of these circuits. In this study, a new full adder and subtractor design using unique 3-input XOR gate with cells redundancy is proposed. This designs can be utilized to form different expedient QCA layouts. The structures are formed in a single layer deprived of cross-wiring. Besides, this study is directed to the analysis of the functionality and energy depletion possessions of the outlined full adder and subtractor circuits. For the first time, QCADesigner-Energy (QD-E) version 2.0.3 tool is utilized to find the overall depleted energy. The attained effects with QCADesigner have verified that the outlined design has enhanced functioning in terms of intricacy, extent, and latency in contrast to the earlier designs. Moreover, the redundant form of full adder and subtractor has uncomplicated and robust arrangement competing typical styles.

Proposed Square Lattice Photonic Crystal Fiber for Extremely High Nonlinearity, Birefringence and Ultra-High Negative Dispersion Compensation

Abstract A photonic crystal fiber in square lattice architecture is numerically investigated and proposed for broadband dispersion compensation in optical transmission system. Simulation results reveal that it is possible to obtain an ultra-high negative dispersion of about −571.7 to −1889.7 (ps/nm.km) in the wavelength range of 1340 nm to 1640 nm. Experimentally it is demonstrated that the design fiber covers a high birefringence of order 4.74×10‒3 at the wavelength of 1550 nm. Here, numerical investigation of guiding properties and geometrical properties of the proposed PCF are conducted using the finite element method (FEM) with perfectly match layers. Moreover, it is established more firmly that the proposed fiber successfully compensates the chromatic dispersion of standard single mode in entire band of interest. Our result is attractive due to successfully achieve ultra-high negative dispersion that is more promisor than the prior best results.

A Novel Design for XOR Gate used for Quantum-Dot Cellular Automata (QCA) to Create a Revolution in Nanotechnology Structure

Novel digital technologies always lead to high density and very low power consumption. One of these concepts is Quantum-dot Cellular Automata (QCA), which is one of the new emerging nanotechnology-based on Coulomb repulsion. This article presents three architectures of logical “XOR” gate, a novel structure of two inputs “XOR” gate, which is used as a module to implement four inputs “XOR” gate and eight inputs “XOR” gate using QCA technique. The two inputs, four inputs, and eight inputs QCA “XOR” gate architectures are built using 10, 35, and 90 Cells on 0.008 µm2, 0.036 µm2 and 0.114 µm2 of areas, respectively. The proposed “XOR” gate structure provides an improvement in terms of circuit complexity, area, latency and type of cross wiring compared to other previous architectures. These proposed architectures of “XOR” gate are evaluated and simulated using the QCADesigner tool version 2.0.3.