Discovery leads to more economical sensors

Physics Professor Suresh Sharma
Using the red beam from a helium-neon laser, physics Professor Suresh Sharma and his team have developed a process with potentially huge benefits in the optic communications industry.

In 2000, physics Professor Suresh Sharma made a breakthrough that led to one patent, with another pending, and set the stage for his current research. He found that polymers containing minute droplets (one-thousandth of a millimeter) of liquid crystalline material known as polymer-dispersed liquid crystals, or PDLCs, could detect nuclear gamma-rays and ultraviolet light. Polymers, he explains, are soft and bend easily, and PDLCs are essentially plastics that are synthesized to contain tiny inclusions of liquid crystalline material.

“The PDLCs are so thin and pliable. Visualize a shirt with embedded sensors for nuclear radiation,” he said, noting the potential in homeland security and medicine.

Now Sharma and graduate student Robert Ramsey are focusing on PDLC successors, materials known as holographic polymer-dispersed liquid crystalline materials, or HPDLCs.

Holographic images are three-dimensional, as opposed to two-dimensional, like a photograph. Researchers worldwide are investigating potential applications of HPDLCs, with the goal of making state-of-the-art HPDLC holographic gratings.

Gratings work like prisms in separating out different “colors” of the electromagnetic spectrum. These grating structures are realized by “freezing in” an interference pattern of two interacting coherent laser beams.

Communication signals of different frequencies may be transmitted through a common fiber optic cable and must be separated out in different frequency bands at the receiving end, and certain frequency signals may need blocking. HPDLC gratings help accomplish these tasks with high accuracy.

Sharma and Ramsey’s discovery uses the readily available and economical red beam from a helium-neon laser to accomplish this task. Their research focuses on holographic HPDLC gratings that can be switched on and off quickly by external fields. Commonly, higher energy laser beams (green and uv) are used to make HPDLC gratings.

“But a lower energy laser beam, such as from a helium-neon laser, will make sensors more available and a whole lot cheaper,” Sharma said.

UT Arlington has applied for a patent on the discovery. A Strategic Partnership of Research in Nanotechnology (SPRING) grant funds Sharma’s project in collaboration with the Air Force Research Laboratories, Wright Patterson Air Force Base.

Physics Department Chair James Horwitz says Sharma’s dedication to research and teaching are like the two sides of a coin.

“His research has created great interest in prospective students from around the world,” Horwitz said. “These students regularly write to him, asking if they can come to UT Arlington to pursue research work with him.”

And have the opportunity to impact the world through their discoveries.

— Sue Stevens