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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.

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We propose a novel twelve-channel Dense Wavelength Division Multiplexing (DWDM) demultiplexer, using the two-dimensional photonic crystal (2D PC) with square resonant cavity (SRC) of ITU-T G.694.1 standard. The DWDM demultiplexer consists of an input waveguide, SRC, and output waveguide. The SRC in the proposed demultiplexer consists of square resonator and microcavity. The microcavity center rod radius (Rm) is proportional to refractive index. The refractive index property of the rods filters the wavelengths of odd and even channels. The proposed microcavity can filter twelve ITU-T G.694.1 standard wavelengths with 0.2 nm/25 GHz channel spacing between the wavelengths. From the simulation, we optimize the rod radius and wavelength with linear regression analysis. From the regression analysis, we can achieve 95% of accuracy with an average quality factor of 7890, the uniform spectral line-width of 0.2 nm, the transmission efficiency of 90%, crosstalk of −42 dB, and footprint of about 784 μm2.

In this work, a surface plasmons resonance-based biosensor is theoretically and mathematically investigated. The proposed sensor is a multilayered structure of the titanium disilicide and graphene along with Ag metal. These layers are stacked over the BK7 prism. The metal, titanium disilicide, and graphene layer thickness are taken as 45 nm, 2 nm, and 1.7 nm, respectively. The titanium disilicide is an air-stable 2-D material. The performance of the biosensor is analyzed using the attenuated total reflection (ATR) method. The proposed configuration has a maximum sensitivity of 183.4°/RIU, 47.45 % higher than the conventional sensor. The designed sensor has wide applications in chemical, medical, and biological analyte sensing.

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