DIFFRACTIVE OPTICS

Diffractive optics manipulate the properties of a plane wave by selectively retarding portions of the wave front. This retardation is accomplished with the use of a glass substrate etched with the appropriate pattern. The diffraction by this etched pattern sends the light in the desired direction. The use of diffraction rather than refraction or reflection -- the traditional means by which optical waves are manipulated -- permits a more versatile and powerful means of steering light. 

My interest in diffractive optics, and in the particular class of diffractive optics known as spot array generators, stems from my involvement with the Photonics Group at McGill University and their work on optical backplanes for high performance computing and telecommunication switches. A spot array generator is a diffractive optic component that converts a single point of light into an array of spots, each with a specified intensity and position. In the optical backplane work, spot array generators are used to deliver optical power to arrays of electro-optic modulators. In the work being conducted at McGill, these modulators were GaAs / GaAlAs devices based on the self electro-optic effect. These optical modulators are combined with GaAs or silicon circuitry to provide an interface between conventional electronic circuitry and free-space optical interconnects. 

At MTSU, I am developing an ever-growing suite of software tools for designing two-level and multi-level diffractive optic components. In addition to being a research topic of continuing interest, I've also integrated this work into the Advanced Lab for our Physics majors. In the first such project (Spring semester '96), two students worked on writing a Simulated Annealing Design Code for simple diffractive optic spot array generators in Mathematica©. The designs were plotted out on transparencies using a laser printer to make amplitude gratings. These amplitude gratings were then characterized optically in the lab.