Improving the Performance of 2-To-4 Optical Decoders Based on Photonic Crystal Structures

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.

Photonic crystal-based decoders: ideas and structures

“…level was increased from 82 to 99% for output ports, which is more than in other works [7][8][9][10][11][12][13][14]. Also, the size of the device is 228 μm 2 more compact than some works [12,13].…”

“…The amount of their contrast ratio, time analysis, and area distinguishes them from each other. There is a report of a 2-to-4 decoder which is constructed by eight waveguides, which are connecting two input ports, X and Y to four output ports, O0, O1, O2, and O3 (see Figure 3a) [7]. One bias signal from port E is applied to the waveguide W1 for interfering with two signals coming from input ports through the waveguides W2 and W3.…”

“…Unlike the two previous decoders with square lattice [7,8], the two following decoders [9,10] present a triangular lattice of the two-dimensional photonic crystal (a) A top view of the structure including four resonant cavities connected to W5, W6, W7, and W8 [7] (b) magnifying the cross-connection for inputs X and Y [7].…”

“…The important parameters of the mentioned works are summarized in Table 2. It can be seen that references [7][8][9][10] which are based on cavities have smaller sizes than references [11][12][13][14], which are designed by resonant rings. According to the published works and Table 2, it is recommended a lattice form and a cavity-based resonator to design the photonic crystal decoders with fast response and small area.…”

Large omnidirectional mid-infrared photonic bandgap in a one-dimensional ternary photonic crystal consisting of isotropic dielectric, elliptical metamaterial and plasma

“…By tuning the geometric parameters of PhCs, the wavelength ranges of PBGs can be flexibly controlled [4]. By virtue of their prohibition property for light propagation, PBGs have been widely utilized to design various optical devices, such as lasers [5,6], fibers [7,8], absorbers [9][10][11][12][13][14], filters [15][16][17][18][19], sensors [20][21][22][23][24], polarization selectors [25,26], electro-optical encoders [27], optical decoders [28], all-optical flip-flops [29], and multiplexers [30,31]. Omnidirectional photonic bandgaps (OPBGs) represent the intersections of wavelength ranges of PBGs at all the incident angles [32].…”