Title

Diffraction of a Zeroth-Order Bessel Beam with a Transmission Grating

Date of Award

2021

Document Type

Thesis

Degree Name

Master of Science in Physics

Department

Physics

First Advisor

Raphael A. Guerrero, PhD

Abstract

Bessel beams possess interesting properties such as non-diffraction and the ability to self-heal after encountering an obstacle. Such beams have proven useful in applications such as materials processing and optical micromanipulation. In this study, propagation properties of Bessel beams were modified via an optical system that employed commercial diffraction gratings. Bessel beams were generated with an annular slit-lens technique with output beams made to propagate through 100 lines/mm, 300 lines/mm and 600 lines/mm transmission gratings. The maximum propagation distance has a theoretical value of 110 cm for 100 lines/mm, 36 cm for 300 lines/mm and 18 cm for 600 lines/mm, compared with a maximum theoretical distance of 120 cm without a diffraction grating. Experimental maximum propagation distance is almost 50 cm when the Bessel beam travels through the gratings. Bessel beams propagating through diffraction gratings exhibit non-diffraction over an appreciable distance and self-reconstruction. Additional beams are created at diffraction orders m = 1 and m = -1. For Bessel beams diffracted by gratings, core diameters are reduced but self-reconstruction is faster compared to free-propagating beams. Beam propagation is dependent on the number of slits: the higher the number of slits, the larger the cone angle leading to a smaller core diameter. In terms of self- reconstruction, the beam profile recovers faster since the beam spreads out more due to diffraction compared to free-propagating beams.

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