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
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.