New approaches to the design and implementation of diffractive optical elements
Abstract
This work has focused on the design and implementation of diffractive optical elements, particularly, the phase elements, using iterative techniques. In the case of synthesizing computer-generated holograms, a new technique which is a combination of the modified input-output algorithm and the iterative interlacing technique has been shown to be effective in reducing the reconstruction error and speeding up the convergence time. To improve the technique, an analysis is performed in investigating the possibility of combining the proposed technique with the projections on to constraint sets algorithm. Meanwhile, an extension of the proposed technique, iterative interlacing error diffusion algorithm, is successfully implemented. In the second half of the research, a new iterative optimization method based on the Yang-Gu (Y-G) algorithm for the design of diffractive phase elements (DPE's) which incorporate several optical functions is presented. Based on a rigorous mathematical derivation, an iterative algorithm is developed to integrate several functions into one DPE. Two sets of examples are carried out through numerical simulations. In the first set of examples, several one-dimensional (1-D) DPE's capable of both demultiplexing different wavelength components and focusing each component wave were designed. In the second example, a successful design of a two-dimensional (2-D) DPE which performs as a demultiplexer in one direction and an array generator in the other direction was illustrated. The parallel implementation of the algorithm on the MASPAR machine and further simulation results were also addressed. Experimentally, the electron-beam lithography and reactive ion etching (RIE) has been used to fabricate several reflective phase gratings with four quantization levels to investigate the sensitivity of diffraction efficiency to the experimental error in the etched depth and the alignment problem.
Degree
Ph.D.
Advisors
Ersoy, Purdue University.
Subject Area
Electrical engineering
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