I= A STUDY IN THE COHERENCE PROPERTIES OF PARTIALLY COHERENT BEAMS
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Title of Thesis
A STUDY IN THE COHERENCE PROPERTIES OF PARTIALLY COHERENT BEAMS

Author(s)
Muhammad Zahid
Institute/University/Department Details
Department of Physics/ Quaid-i-Azam University, Islamabad
Session
1989
Subject
Physics
Number of Pages
112
Keywords (Extracted from title, table of contents and abstract of thesis)
coherence properties, partially coherent beams, nonlinear optics, bessel-gauss beams, second-harmonic generation, diffraction free beams, partially coherent pump

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.

Download Full Thesis
1776.43 KB
S. No. Chapter Title of the Chapters Page Size (KB)
1 0 Contents 0
133.75 KB
2 1 Introduction 1
117.7 KB
  1.1 Partially Coherent Beams 1
  1.2 Generalized Schell-Model Source 6
  1.3 Bessel-Gauss Beams 7
  1.4 Second-Harmonic Generation by Partially Coherent Beams 9
3 2 Second-Order Coherence Properties Of Beams Generated By A Generalised Schell-Model Source 11
333.51 KB
  2.1 Introduction 11
  2.2 Partially Coherent Source 15
  2.3 Gaussian Schell-Model Source 17
  2.4 Anisotropic Gaussian Schell-Model Source 21
  2.5 Second-Order Degree of Coherence of Fields Generated by a Generalized Schell-Model Source 25
  2.6 Intensity Distribution and the Moments of the Mean-Square Beam Radius 26
4 3 Study Of The Partially Coherent Bessel-Gauss Beams 35
251.33 KB
  3.1 Introduction 35
  3.2 Diffraction Free Beams 36
  3.3 Bessel-Gauss Beams 39
  3.4 Evaluation of Coherence Function 42
  3.5 Second-Order Moment of Mean-Square Beam Radius 45
  3.6 Discussion 47
5 4 Coherence Properties Of Second-Harmonic Beams Generated By A Partially Coherent Pump 52
306.93 KB
  4.1 Introduction 52
  4.2 The Coupled Amplitude Equations 53
  4.3 Model for The Partially Coherent Pump Beam 56
  4.4 Second-Order Correlation Function for The Second-Harmonic Field 57
  4.5 Mean-Square Radius of The Second-Harmonic Beam 62
  4.6 The Mean-Square Coherence Radius Of The Second-Harmonic Beam 64
  4.7 Conversion Efficiency 65
  4.8 Discussion 67
6 5 References 74
760.12 KB
  5.1 Appendix-A 77
  5.2 Appendix-B 83
  5.3 Appendix-C 97