Abstract
In this study, a novel, two-dimensional photonic crystal-based structure for the 2-to-4 optical decoder is presented. The structure consists of 23 rows and 14 columns of chalcogenide rods that are arranged in a square lattice with a spatial periodicity of 530 nm. The bias and the optical signals are guided toward the main waveguide through the three waveguides. Two unequal powers are applied to the input ports to approach the different intensities proportional to four working states into the main waveguide. Four cavities including the nonlinear rods are in response to drop the optical waves toward the output ports. To calculate the band diagram and the spatial distribution of the electric and magnetic fields, the plane wave expansion and the finite difference time domain methods have been used. The delay time of the designed structure is obtained around 220 fs, which is less than one for the previous structures. Furthermore, the gap between the margins for logic 0 and 1 is equal to 83%, which is higher than one for other works. Besides, the area of the structure is reduced to 90 µm2 in comparison to all reported structures. Based on the mentioned results, it seems that an improvement of the performance for 2-to-4 optical decoders has been obtained in this research.
Highlights
Optical systems have been proposed to obtain high-speed transmission and ultra-fast processing [1,2]
One bias and two input signals were guided to the main waveguide of the device
Due to using the nonlinear rods with the different radii in four cavities, the dropping operations for the optical intensity of I0, 2I0, 3I0, and 4I0, were obtained through four waveguides connected to the main waveguide
Summary
Optical systems have been proposed to obtain high-speed transmission and ultra-fast processing [1,2]. The structure correctly presented the decoding operation for two input ports, the time analysis was not completed, so the delay time and the difference of margins for logic 0 and 1 were not reported Another structure based on five resonant rings for 2-to-4 decoders was proposed by Crystals 2019, 9, 635; doi:10.3390/cryst9120635 www.mdpi.com/journal/crystals. A structure based on four resonant rings was presented by Mehdizadeh et al in which the silicon rods were placed in the form of 49 rows and 41 columns [13] They used nonlinear rods in the rings to approach the optical Kerr effect and the dropping operation of optical waves toward the output ports. The dropping operation of optical waves is done by using the resonant rings, which result in a larger area and more delay time.
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