Date of Award

9-9-2023

Document Type

Thesis

School

School of Electrical & Electroncis Engineering

Programme

Ph.D.-Doctoral of Philosophy

First Advisor

Dr.S.Sriram

Second Advisor

Dr.K.Sangeetha

Keywords

Single Crystals, Second Harmonic Generation Efficiency, Z-Scan Study, Nonlinear Coefficient, Optical Limiting Behavior

Abstract

Crystal growth has attained the pinnacle of a point in the current research owing to the requirement of the single crystals in the frontier field of nonlinear optics. Organic crystals exhibit high transparency, high laser damage threshold and de-localized π electron cloud. But they possess weak mechanical stability. In contrast, the inorganic crystals exhibit magnanimous mechanical and thermal properties but have modest nonlinear optical property. If we combine these two materials, then we can obtain the semi-organic materials.

Among the organic materials, the amino acids are chosen and they are mixed with inorganic material potassium penta borate octa hydrate. They have witnessed a consistent and continuous increase of potential applications in devices used in the areas of optical data storage, optical computing, electro-optical switches and high-speed information processing.

Non-linear optics is the study of how the intensity of light interacts with matter. The discovery of laser opened the doorsteps of nonlinear optics. Semi-organic single crystals behave nonlinearly to the laser radiations thereby showing spectrum of applications such as second harmonic generation, third harmonic generation, frequency mixing, frequency conversion and optical limiting etc.,

Having motivated with the aim of this work is to investigate the potassium penta borate based semi-organic materials for nonlinear applications. The slow evaporation technique was adopted to synthesize the crystals. Potassium penta borate octa hydrate was mixed with the amino acids L-Valine and L-Proline. Also, the methyl orange dye was doped with potassium penta borate octa hydrate. The resulting crystals are

1. L-Valine Potassium Penta Borate octa hydrate (LVPPB)

2. L –Proline Potassium Penta Borate octa hydrate (LPPPB)

3. Pure and Methyl Orange dye doped Potassium Penta Borate octa hydrate (Pure PPB and MOPPB) These crystals were subjected to structural, mechanical, thermal, linear and nonlinear characterizations to use them for NLO Applications. The results obtained are presented and discussed in this thesis.

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