In this paper, the impact of variation in the number of quantum wells and barrier layers on optical properties of GaN/AlGaN based light-emitting diode (LED) is investigated while keeping the width of the active region constant. The number of quantum well and barrier layers are varied from one to six. Simulations are carried out in TCAD software and it is observed that output optical power first increases to a certain number of quantum well layers in the LED and beyond it there is no significant increase in the output power. Output power is increased by 44% when the quantum well layer increases from three to four, thereafter it starts decreasing. On the other hand, the maximum intensity of light continuously decreases with an increase in the number of quantum well layers. The number of layers after which the optical power saturates or decreases is device-specific.
A design of two-dimensional hybrid photonic crystal fiber (PCF) with elliptical and circular air holes and its analyses for large flattened dispersion and high birefringence is presented. The PCF has hexagonal layout with triangular lattice. There are five rings around the solid core. The inner three rings around the core have elliptical air holes while the outer two rings have circular air holes. Three such layouts are designed, analyzed, and compared with the layout having only circular air hole using full-vector finite difference time domain method. The layout with hybrid structure having combined elliptical and circular air hole gives a large flattened dispersion of the order of 4.88 ps/nm/km for the wavelength range of 1.2 to 1.8 μm and magnitude of modal birefringence is 1.238×10−3 at 1.55-μm wavelength.
A vibration-based piezoelectric energy harvester has received increasing attention as a potential power source for microelectronics because of its simplicity of design, operation, and fabrication of devices using microelectromechanical system (MEMS) technology. Energy harvesting provides unending sources of energy for low-power electronics such as wireless sensor nodes where replacement of batteries is not practically possible. Piezoelectric energy harvesters are widely considered because of their compact design, compatibility to MEMS devices, and ability to respond to a wide range of frequencies freely available in the environment. A model for cantilever-based piezoelectric energy harvester is designed and optimized by investigating the effect of seismic mass geometry on the potential generated. The effect of the shape geometry of the seismic mass on the resultant potential generated due to center of mass shift is calculated and compared. A seismic mass with a triangular-shaped geometry with fields concentrated at the tip of the triangle gives a resultant center of mass for a cantilever structure and the seismic mass at a higher point as compared with the rectangular or pyramidal shapes that were investigated. This shift in the center of mass of the combined geometry (cantilever beam and seismic mass) toward the applied pressure results in exerting a higher force and thus increasing the potential. This paper reports that an increased potential of 0.0533 V at a boundary load of 1 bar pressure (minimum feasible pressure) is generated by the energy harvester when a triangular-shaped seismic mass is used; this innovative shape is also compared with other geometries.
The two dimensional Photonic crystal fiber (PCF) with a triangular lattice cross-section pattern of circular air hole
is investigated for four and five layer by the use of finite difference time domain (FDTD) method to investigate the
single mode property and the effect on it by increasing the number of layer as well as by varying the air hole diameter.
In this paper, design of an all-optical switch using MZI switching elements with SOA's and its works performance is
explained. The effect of variations of output power with respect to control signal wavelength, data signal power and control
signal power are examined and plotted. Also the optical spectrum and time domain analysis has been done to demonstrate its
operational features.
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