A STUDY IN THE COHERENCE PROPERTIES OF PARTIALLY COHERENT BEAMS

Muhammad, Zahid (1989) A STUDY IN THE COHERENCE PROPERTIES OF PARTIALLY COHERENT BEAMS. Doctoral thesis, Quaid-i-Azam University, Islamabad.

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Abstract

The theory of partial coherence is a field of interest due to its applications in many branches of physics. In this dissertation we present results concerning the coherence properties of partially coherent beams generated by random phase screens and their applications in the field of nonlinear optics. We present a model for the partially coherent source, referred to as the generalized Schell-model source, in which the phase correlation for the field is Gaussian. We evaluate the mth-order moment of the mean-square beam radius for this model. The second-order moment of beam radius is the same as in the case of well studied Gaussian Schell-model source. However the higher-order moments are different. Next we consider a partially coherent Bessel-Gauss beam of zeroeth order, which is a superposition of Gaussian beams, whose axes are uniformly distributed on a cone. We discuss the directionality of such beams and it is found that a diffraction-free beam can be produced even from a globally incoherent source. Finally we consider second-harmonic generation by a partially coherent beam and evaluate the expressions for the mean-square beam radius, mean-square coherence radius and the conversion efficiency of the emerging beam. We show that the conversion efficiency is enhanced by degrading the coherence of the pump beam. We also show that the coherence properties of the second-harmonic beams are controlled by the pump beams.

Item Type: Thesis (Doctoral)
Uncontrolled Keywords: coherence properties, partially coherent beams, nonlinear optics, bessel-gauss beams, second-harmonic generation, diffraction free beams, partially coherent pump
Subjects: Q Science > QC Physics
Depositing User: Muhammad Khan Khan
Date Deposited: 27 Oct 2016 07:38
Last Modified: 27 Oct 2016 07:38
URI: http://eprints.hec.gov.pk/id/eprint/2890

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