Amel Labbani

The purpose of this paper is to examine the design, simulation, and optimization of a demultiplexer optical system using photonic crystal resonators. Utilizing the distinct properties of photonic crystals, the proposed device achieves high-quality resonances, efficient wavelength separation, and minimal crosstalk. These characteristics are crucial for enhancing the performance of dense wavelength division multiplexing (DWDM) systems, which require precise and efficient channel separation to manage increasing data traffic. Extensive simulations conducted with the RSoft CAD tool explore the impact of varying resonator parameters such as refractive index, geometric dimensions, and material composition on the device's performance. The results indicate substantial improvements in transmission efficiency and quality factor, with average values of 98.675% and 3131.125, respectively. Furthermore, the ability to fine-tune these parameters allows for the customization of the demultiplexer to specific wavelength ranges, making it highly adaptable for various telecommunications applications. This research aims to propel the development of compact, high-performance photonic devices that meet the growing demands of modern communication networks, ultimately contributing to more efficient and reliable optical communication systems.

This paper attempts to investigate the design of a modified Y-shaped demultiplexer based on photonic crystal. The designed structure is used to select four telecommunication wavelengths. In our design, four resonant cavities (RC)are utilized. A square lattice of silicon (Si) rods immersed in air matrix is used as a fundamental structure. Thus, our study is to investigate the effect of various design parameters on the output frequency. To simulate the performance of the proposed device, the Finite Difference Time Domain (FDTD) approach is used. The obtained results show that the average power transmission, quality factor, channel spacing, crosstalk, and full width at half maximum, are 99.925 %, 4638.785, 19.6 nm, from -40,119 to -24,316 dB, and 0.325nm, respectively. Additionally, the proposed demultiplexer is very compact with a total footprint of 269µm², which is very suitable to be utilized in compact photonic integrated circuits (PIC).

In this paper, a novel method to diminish the coupling length and enhance the coupling coefficient in a two-dimensional (2D) photonic crystal (PC) directional coupler (DC)is investigated. The DC comprises two closely spaced linear waveguides separated by one row of silicon columns. In this new approach, we used core/shell (C/S) rods between the waveguides to reduce the coupling length. The C/S rod is obtained by etching a hole in the middle of the silicon rod. This modification leads to a very short coupling length of 5a, where a is the lattice constant of the structure. Simulation results show that increasing the inner core radius increases the coupling coefficient. The coupling properties have been numerically simulated and analyzed using the finite difference time domain (FDTD) and the plane-wave expansion (PWE) methods. Based on the modified structure, we analyzed the output spectrum of a very compact channel drop filter. The proposed modified design would offer significant potential for novel ultrasmall devices based on photonic crystal couplers.

In this paper we investigate a new design of high sensitivity photonic crystal temperature sensor (PCTS). A square lattice of silicon (Si) rods immersed in air matrix is used as a basic structure. The designed sensor consists of two inline quasi-waveguides which are coupled to a resonant cavity (RC). The sensing principle is based on Si refractive index change caused by the variation of the temperatures over a range from 0 to 80 • C. This variation leads to an important shift in the resonance wavelength. The performance of the suggested temperature sensor has been analyzed and studied using finite-difference time domain (FDTD) method. The results show that our designed structure offers a high sensibility of 93, 61 pm/ • C and quality factor of 2506.5. Its structure is very compact with total size 115.422 µm 2 , which is suitable for nanotechnology based sensing applications.

Journal of Nano- and Electronic Physics. Scientific journal. ISSN: 2077-6772. Journal abbreviation: J. Nano- Electron. Phys. No page charges. All articles are freely available on-line. Issued 4 times per year. Publisher: Sumy State University. (Sumy, Ukraine)

In this paper a T-branch optical diplexer in two dimensional (2D) photonic crystal (PhC) to select two telecommunication wavelengths 1493.6nm and1553nm is investigated. In our design directional couplers (DC) and resonant cavity (RC) are utilized. A square lattice of silicon (Si) rods in air is used as fundamental structure. The coupling regions consist of three entire rows of decreased Si rods. Plane wave expansion method (PWE) and finite difference time domain (FDTD) method are utilized to analyze and simulate the characteristics of the designed device. The average transmission efficiency of our proposed diplexer is about 99.75%. High quality factor and extremely small crosstalk were achieved. The total size of the suggested design is 272.214 μm², which is very suitable for nanotechnology based demultiplexing applications.