Design and Numerical Analysis of an All-optical 4-channel Power Splitter in E, S, C, L, and U Bands via Nano-line Defects in Photonic Crystal

Abstract

AbstractIn the present study, the propagation of electromagnetic waves in a square-lattice photonic crystal waveguide (PCW) is investigated using the finite-difference time-domain (FDTD) method. Then, the plane wave expansion (PWE) method is utilized to calculate the 2D photonic crystal band structure. To realize the desired waveguide, nano-line defects are introduced. The results of the numerical simulations and optimization scanning indicate that for the proposed photonic crystal structure consisting of silicon circular dielectric rods with a radius of 84 nm, a band gap can be achieved in the wavelength range of 1.34 μm<λ<1.93 μm. This wavelength range covers E, S, C, L, and U communication bands. Subsequently, by eliminating the rods in four parts of the structure, an all-optical 4-channel splitter can be designed. The numerical simulation results indicate that by coupling a light source to the main path of the structure and propagating it through each channel, the powers of the 4 output facets become approximately the same. The output power of channels 1 and 2 equals to 24.5 % of the input power, and the output power of channels 3 and 4 is 21 % of the input power and the remaining 9 % is lost in the structure as the leakage power. Since the 1.55 μm wavelength is within the band gap, that is the telecommunication band C, this device can be used as a power splitter.