Faculty Profile: Michael Henry

Nonlinear Materials for Photonic Devices

Michael Henry joined our department in the Fall of 1995. He comes to us from the U.S. Virgin Islands by way of Cincinnati, Ohio, where he acquired a Bachelor's degree from Xavier University, and also by way of Huntsville, Alabama, where he earned a Ph.D. from Alabama A&M University. At Alabama, he specialized in nonlinear optics, concentrating in organic materials. He used such experimental techniques as four wave mixing, second harmonic generation, self focusing, self phase modulation, self diffraction, spectroscopy, and Langmuir-Blodgettry.

Dr. Henry is interested in research that can be directly applied to industries, for example communications and computers. However, like all physicists he is driven to understand the underlying physical process of any system which may be useful for a particular application. Research with direct application to industry will train students to contribute to private industry, will help open the job market to new physicists, and will appeal to physicists who desire to work on projects in private industries having applications in today's world.

Dr. Henry is studying nonlinear materials and systems which may be used in photonic devices. Some of the possible photonic devices are image processors, multiplexers, optical switches, optical modulators and optical logic gates. At the present time, these devices are electronic. However, photonic counterparts may have advantages over the electronic devices. The possible advantages are similar to the advantages of replacing copper cable with fiber optical cables in the communications industry.

There is a quest to find efficient materials for photonic devices, materials that will play much the same role that silicon and gallium arsenide play in electronic devices. In this effort, research is taking place on two fronts. New materials are being synthesized with the hope of finding an efficient material. And experiments are being carried out in order to better understand the nonlinear interactions. In understanding the nonlinear process the materials can be successfully manipulated to achieve more efficient results.

Several techniques are used in the lab to identify and characterize nonlinear materials. These techniques include four-wave mixing, self-phase modulation and third-harmonic generation. In order to characterize and efficiently utilize the materials, the nonlinear system must be fully understood. Dr. Henry's lab studies the various nonlinear effects that take place in the materials such as quantum starks confinement, saturation absorption, and excited state absorption. Once the materials have been identified and characterized, they are used in systems that will lead to devices. Presently, Dr. Henry is working with dye-doped organic thin films and multiple-quantum-wells thin films. These films will be tested in image processing, modulation and logic systems.

On the second front, Dr. Henery is examining the various nonlinear interactions of the materials in the hopes of manipulating the interaction in order to make it more efficient. The effects of optical feedback on the nonlinear processes taking place in the materials are being studied. Optical feedback can stem from processes such as fluorescence distributive feedback. The process is dependent on the physical material. This work should give a clearer view of nonlinear process in these thin films.

There is also an effort to begin a research program in optical fibers. Dr. Henry is interested in nonlinear processes in fibers. These nonlinear processes include four-wave mixing, and Raman and Brillouin scattering. These nonlinear effects are sometimes useful in lightwave communications, for example in wavelength conversion in wavelength division multiplexing. In some cases the nonlinear effects are harmful. These nonlinear effects can lead to the generation of wavelengths different from the wave that contains the transmitted information, leading to improper data transfer. The ability to control these effects by turning on and off the nonlinear effect is of interest. Hopefully this research effort will lead, in the classroom, to the development of a fiber and planar waveguide course.*