A highly birefringent photonic crystal fiber (PCF) with large nonlinearity, low dispersion and low confinement loss is designed by introducing a solid elliptical core structure with spiral lattice of circular air holes as a cladding. The dependence of different geometrical parameters, such as pitch size, diameter of air holes and arrangement of air holes are investigated. By optimizing the available parameters, the designed elliptical–spiral PCF offers high birefringence up to 0.005264, high nonlinearity up to 8683.59[Formula: see text]W[Formula: see text][Formula: see text]km[Formula: see text], low chromatic dispersion of [Formula: see text][Formula: see text]ps/nm/km, and low confinement loss of 0.00305[Formula: see text]dB/km within a wide wavelength range of 1000–2000[Formula: see text]nm.

In this article, photonic crystal (PhC) based all-optical logic gates, namely AND, OR and EX-OR have been explored and their characteristics are reported. Two-dimensional (2D) PhC based logic gates are proposed using a hexagonal lattice with T-shaped structure by incorporating line defects. The total size of the device is 84 µm2 and it operates at a wavelength of 1550 nm (C band). The designed optical logic gates are investigated using 2D finite difference time domain simulators by means of the plane wave expansion method. Parameters, such as response time and contrast ratio of the designed all-optic logic gates, are analyzed. The proposed AND, OR and EX-OR logic gates offer a contrast ratio of 14.48 dB, 14.57 dB and 12.9 dB respectively with, in order, response times of 0.159 ps, 0.168 ps and 0.1672 ps. The designed logic gates work in the third optical window as they are operating at the 1550 nm wavelength. To specify the performance of the proposed logic gates, their field distribution has been determined and is exhibited. The designed logic gates are suitable for use in photonic integrated circuits, all optical computing and optical sensing applications.

No abstract

No abstract

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.