Sumita Deb

Broadband fractional total internal reflection quasi phase matching based second harmonic generation in reverse tapered isotropic semiconductor considering the effect of nonlinear reflection

This paper analyzes a highly efficient broadband second-harmonic generator in the mid infrared region using an isotropic reverse tapered semiconductor slab configuration, using fractional total internal reflection quasi-phase matching technique. A computer aided simulation has been performed using ZnTe as the nonlinear material which provides an extremely high conversion efficiency of 22.94% with a 3dB bandwidth of 200nm. Effect of varying the slab dimensions on the performance parameters has also been analyzed. Finally, the catastrophic effect caused by destructive interference due to nonlinear law of reflection has also been incorporated in the analysis thereby giving more accurate results.

Total internal reflection quasiphase matching-based broadband second harmonic generation in a plane-parallel uniaxial crystal of lithium niobate

Abstract. The present work analytically investigates the generation of broadband second harmonic (SH) using total internal reflection (TIR) quasiphase matching technique in a plane-parallel uniaxial crystal having optic axis nonparallel with respect to the horizontal base. A computer-aided simulation has been performed using lithium niobate as the nonlinear material to determine the possibility of generating broadband SH intensity when broadband fundamental laser radiation is allowed to undergo TIR inside the crystal. The simulated results indicate a peak conversion efficiency of 5.22% with a spectral bandwidth (BW) of 116 nm, centered at 2.258  μm in a 10-mm-long slab. The effect of variation in operating temperature, crystal length, crystal thickness, angle of deviation of optic axis, and angle of incidence of fundamental beam at the air–prism interface on efficiency and BW of resulting SH output has been studied.

An analysis on broadband SHG using TIR-QPM in a multi-tapered slab of ZnSe in mid-IR region

An enhanced broadband conversion scheme is analytically described in a multi-tapered profiled Zinc Selenide (ZnSe) slab for Second Harmonic Generation (SHG) using Total Internal Reflection Quasi Phase Matching (TIR-QPM) with due consideration to the optical losses (absorption losses, reflection losses and Goos-Hänchen shift). The effects of variation of the tapering angles and the vertical heights of the ZnSe slab has been studied for generated SHG. Optimizing these parameters, a wider broadband frequency converter with appreciable conversion efficiency can be designed.

Voltage stability analysis using reactive power loading as indicator and its improvement by FACTS device

Voltage stability is one of the important issues of power system. Voltage stability should be maintained for secure operation of power system. Bus voltages regarding maximum reactive power loading is used in this paper for analysis of voltage stability. To test the applicability of the concerned method the reactive loads are increased by a constant factor. The proposed technique is applied on standard IEEE 14 bus test system. Load flow analysis of Newton Raphson method is coded in MATLAB programming for finding different parameters of the system and utilised for the stability analysis. The result from the proposed index is also verified by another standard indicator named ‘reactive power sensitivity index’. Test results show the effectiveness of the proposed technique. FACTS device is utilised in the weakest bus to improve its voltage stability.

Voltage stability assessment in radial distribution system by line stability indicator (LSI) and its improvement using SVC

Load demands on distribution system is growing rapidly. So, the distribution system is operating nearer to the stability boundary. A stability index named line stability indicator (LSI) is developed in this paper for voltage stability analysis of radial distribution system. The applicability of the indicator is tested on a standard (IEEE) 33-bus Radial Distribution System. To find the value of proposed indicator for different lines of the system under consideration MATLAB code is used. This indicator is able to find the weak lines of the system. By using FACTS device at the receiving end side of the weak line the voltage level of buses of the system can be improved. Results indicate that installation of FACTS device at the appropriate bus will make the whole system more stable in respect of voltage.

Numerical analysis of destructive interference effect due to nonlinear law of reflection in a wedge shaped zinc telluride slab for total internal reflection quasi phase matching basesd broadband second harmonic generation

In this paper the destructive interference effect due to nonlinear law of reflection has been analyzed numerically in a wedge shaped zinc telluride slab for total internal reflection quasi-phase matching based second harmonic generation, using ppp polarization configuration. The computer aided simulation indicates 3 dB bandwidth of 360 nm, centred at 8.292 μm, with conversion efficiency of 8.27 %. When the destructive interference effect due to nonlinear law of reflection along with various optical losses are considered, the peak second harmonic conversion efficiency sharply reduces to 1.5 % with a corresponding 3 dB bandwidth of 351 nm, centred at 8.247 μm.

Broadband second harmonic generation using tota internal reflection quasi phase matching for ppp, pss and spp polarization configurations

In this paper broadband second-harmonic generation has been compared analytically in a tapered zinc telluride slab using total internal reflection quasi-phase matching for ppp, pss and spp polarization configurations. The simulated results, considering various optical losses, in terms of 3 dB bandwidth and conversion efficiency have been presented. For given slab dimensions, ppp configuration seems to be the favourite choice in terms of both the performance parameters. However, by varying the polarization nature of the three interacting optical waves, one can obtain a broadband spectrum at different frequency domain.

Quasi-Phase Matched Second-Harmonic Generation in Telluride Compounds Using Total Internal Reflection

We analytically describe quasi-phase matched second-harmonic generation in the mid-IR region in a parallel isotropic semiconductor slab made of Zinc Telluride (ZnTe) and Cadmium Telluride (CdTe) using total internal reflection quasi phase matching technique. The simulated results indicate conversion efficiencies of 4.08% (centered at 8.495 -mm-long slab of ZnTe and CdTe respectively. The losses due to surface roughness, Goos-Hanchen shift and absorption of the slab have been considered in the analysis. The effect of variation in the angle of incidence has been studied for both the materials. Keywords-second-harmonic generation, total internal reflection, quasi phase matching, isotropic, zinc telluride, cadmium telluride.

Determination of Phase Matching Angle for Non- Resonant Total Internal Reflection Quasi-Phase Matching in a Parallel Slab using Matlab/Simulink Software

The simulated model calculates the phase matching angle for a parallel isotropic slab made of Zinc Telluride (ZnTe), Cadmium Telluride (CdTe), Gallium Arsenide (GaAs) wavelength of 10.6 μm by determining the wave-vector mismatch. The model also generates the status of fulfillment of Total Internal Reflection (TIR) inside the semiconductor slab. The simulated results indicate phase matching angle of 0.9034 rad for a slab thickness of 800 μm in case of ZnTe and 0.5457 rad for CdTe taking the slab thickness as 500 μm. The phase matching angle for ZnSe is 1.481 rad and that of GaAs is materials. For all the cases, the TIR condition is found satisfying. KeywordsWave-vector mismatch, Phase matching, Quasi phase matching, Isotropic, Total Internal Reflection Quasi Phase

Broadband Second-Harmonic Generation in the Near-Infrared Region in a Tapered Zinc Selenide Slab Using Total Internal Reflection Quasi-Phase Matching

We analytically describe the concept of broadband second-harmonic generation in the near-IR region in an isotropic tapered semiconductor slab made of zinc selenide. A computer-aided simulation has been carried out to determine the possibility of generating broadband second-harmonic intensity when broadband fundamental laser radiation is allowed to undergo total internal reflection inside the tapered semiconductor slab. The simulated results indicate an extremely broad spectral bandwidth of 557 nm centered at 4.05 µm (3.812 to 4.369 µm) in a 10-mm-long slab with a conversion efficiency of 0.02%. The losses due to absorption and surface roughness of the semiconductor material have been considered in the analysis. The effects of variations in the temperature, length, and tapering angle of the semiconductor slab have been studied for the generated second-harmonic radiation.