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Third-order optical Nonlinearity and optical Power limiting of organic Materials under cw laser Illumination

Pramodini, S (2015) Third-order optical Nonlinearity and optical Power limiting of organic Materials under cw laser Illumination. Phd. Thesis thesis, Manipal Institute of Technology, Manipal.

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Abstract

With the development of laser technology, nonlinear optical materials are of particular importance in the field of science and technology. The present work exploits the possibility of Anthraquinone dyes, Conducting polymers and Copolymers of Aniline as third-order nonlinear materials for opto-electronic device applications. Synthesis of π- conjugated polymers and copolymers were carried out in sulphuric and hydrochloric acid medium. UV-VIS and FTIR spectroscopic techniques were adopted to elucidate the structure of synthesised compounds. The sign and magnitude of χ(3) were evaluated by employing standard z-scan technique. CW He-Ne laser operating at 633 nm wavelength was used as source of excitation. The observed nonlinear absorption and refraction nonlinearities were due to reverse saturable absorption and self-defocusing behaviour. The structure-property relationship for the enhancement of optical nonlinearity is discussed in detail. Optical power limiting, diffraction rings and induced spot size variation studies were conducted to determine the limiting threshold, clamping values and thermal lensing effect. A good optical limiting and clamping of about 0.9 mW and 0.05 mW were achieved. Thus, this work is a contribution to Optics and Photonics Physics, which exploits π-conjugated materials for device applications.

Item Type: Thesis (Phd. Thesis)
Subjects: Engineering > MIT Manipal > Physics
Depositing User: MIT Library
Date Deposited: 09 Apr 2016 14:19
Last Modified: 09 Apr 2016 14:19
URI: http://eprints.manipal.edu/id/eprint/145794

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