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Optical Design & Engineering

A Career in Polarization

Rasheed Azzam, 2005 recipient of the G.G. Stokes Award, talks about his work in optical polarization.

From oemagazine October, 2005
30 October 2005, SPIE Newsroom. DOI: 10.1117/2.5200510.0013

Rasheed M. A. Azzam, University of New Orleans (UNO), LA, is this year's recipient of the SPIE G.G. Stokes Award for his career-long work in optical polar-ization. "I consider it a special honor to receive this award, which is named after the distinguished mathematical physicist George Gabriel Stokes," Azzam says.

Rasheed Azzam (left) at Bibliotheca Alexandrina, with a group of participants in the Einstein Symposium, Alexandria, Egypt, 4-6 June 2005.

Among Azzam's many technical accomplishments is the invention of the four-detector photopolarimeter, the commercial version of which won a Photonics Circle of Excellence Award and an R&D 100 Award.

Azzam has also been active with SPIE, the Optical Society of America (OSA), and the Third World Academy of Sciences (TWAS; Trieste, Italy).

Geometrical Elegance

Though his career spans more than 30 years, his interest in optics began earlier, in secondary school. "I was impressed by the elegance of the geometrical laws of reflection and refraction in high school," Azzam says. "However, my real encounter with optical polarization started in 1969 when I joined what was known then as the Electrical Materials Laboratory at the University of Nebraska-Lincoln [UNL] under the direction of the late Prof. Nicholas M. Bashara."

Azzam received his PhD from UNL in 1971 and co-authored the monograph Ellipsometry and Polarized Light with Bashara in 1977. The book has been translated into several languages and is considered the foremost publication in the field. "I am personally gratified by the favorable reception that this book has had over the years," Azzam says.

Other career highlights include the development of several new techniques to measure optical polarization and the Jones and Mueller matrices. In his PhD dissertation, Azzam introduced generalized ellipsometry (GE) for systematic Jones-matrix measurement. Since then, GE has been widely used to determine optical properties of anisotropic crystal-line materials. He also invented the dual-rotating-retarder Mueller-matrix polarimeter, and contributed to reflection optics and the design of thin-film devices for polarized light.

Outstanding Inventor

In 1985, Azzam published the most papers of his career. "One of those papers, 'Arrangement of four photodetectors for measurement of the state of polarization of light,' appeared in Optics Letters and created a lot of excitement," he says. "In this passive and static scheme, three windowless partially reflective silicon photodetectors are set at oblique incidence to steer an incident light beam in a non-planar light path to a fourth [antireflection]-coated detector. The 4 * 1 output electrical signal vector of this four-detector photo-polarimeter [FDP] is linearly related to the 4 * 1 Stokes vector of incident light by a 4 * 4 instrument matrix, which is obtained by calibration."

The first FDP was built, calibrated, and tested at UNO with support from the National Science Foundation and with the collaboration of Enrico Masetti (Italy) and others. U.S. and international patents were licensed to Gaertner Scientific (Skokie, IL), which manufactures fast kinetic and scanning ellipsometers. Based on the FDP technology, they developed the StokesMeter.

Azzam was named Outstanding American Inventor of 1988 by Intellectual Property Owners Inc. for the invention of the FDP. Gaertner's commercial version also earned him a Photonics Circle of Excellence Award and an R&D 100 Award in 1993.

His recent research has focused on spectroscopic ellipsometry (SE) based on prismatic substrates and diffraction gratings. Working in conjunction with Containerless Research Inc. (Evanston, IL), Shankar Krishnan (now with KLA-Tencor, San Jose, CA), and others, Azzam has developed the patented grating-based division-of-amplitude photopolarimeter (G-DOAP) for spectroscopic and time-resolved measurement of polarization and SE.

In addition, Azzam also teaches undergraduate and graduate classes on circuits, electromagnetics, and optics at the University of New Orleans as a distinguished professor of electrical engineering."I am currently involved with graduate students in the design of beam splitters for DOAP, broadband, and tunable quarter-wave retarders and circular polarization beam splitters for the infrared using total and frustrated total internal reflection," Azzam explains.

Azzam's work with the technical community doesn't end at the lab or in the classroom, however. He is a Fellow of SPIE, the OSA, and the TWAS and has served as editor for OSA journals on topics of polarization as well as editor of SPIE's Milestone Series volume Selected Papers on Ellipsometry. He has also been a co-organizer, co-chair, and co-editor for several international conferences. In fact he co-chaired two of the earliest SPIE polarization conferences and edited their resulting proceedings - Polarized Light: Instruments, Devices, Applications and Optical Polarimetry: Instrumentation and Applications - in 1976 and 1977.