Press Release 07-136
Photonic Gel Films Hold Promise

Sensors, display devices and tunable lasers could benefit

Photonic gel crystals reflect light based on the way their molecules are "tuned." Credit and Larger Version

October 21, 2007

By alternating layers of two different polymers - one rigid and glassy, the other soft and easily swollen with liquid or vapor - researchers funded by the National Science Foundation (NSF) report they've created photonic gel crystals that can be tuned to reflect light of many different colors across the visible and near-infrared spectrum.

The research results, reported in the Oct. 21 online issue of Nature Materials by Principal Investigator Edwin Thomas and his colleagues at the Massachusetts Institute of Technology's department of materials science and engineering, demonstrate the degree to which these photonic materials are tunable through changes in the soft layer's thickness and index of refraction. The responsiveness of the photonic crystals makes them likely candidates for active components of display, sensory or telecommunication devices.

"This is an ingenious and easy-to-implement method for making photonic materials whose optical properties can be readily tuned over a wide range [of the spectrum]," said Andrew Lovinger, director of the polymers program at NSF, which funded this research.

In one example, the researchers show very large, reversible optical changes by varying the salt content of a water solution in which these films are dipped. Multicolor patterns can be made by sequential coating of films, with the color of each region depending on the degree to which their molecules are chemically interconnected.

"We expect these photonic gels will lead to many novel applications, including colorimetric sensors, active components of simple display devices, and electrically controlled tunable optically pumped lasers, photonic switches and multiband filters," Thomas said.

NSF funded the research in 2003 through a three-year grant aimed at creating new nanomaterials that are tunable through magnetic, chemical or other techniques. Following the discovery of intriguing new effects by Thomas and his colleagues involving the interaction of light and sound in these nanomaterials, his grant was extended for two additional years through a "special creativity award."

-NSF-

Media Contacts
Diane E. Banegas, NSF (703) 292-8070 dbanegas@nsf.gov
Anne Trafton, Massachusetts Institute of Technology (617) 253-6936 trafton@mit.edu

Program Contacts
Andrew Lovinger, National Science Foundation (703) 292-4933 alovinge@nsf.gov

Principal Investigators
Edwin Thomas, Massachusetts Institute of Technology 617-253-6901 elt@mit.edu

The National Science Foundation (NSF) is an independent federal agency that supports fundamental research and education across all fields of science and engineering. In fiscal year (FY) 2009, its budget is $9.5 billion, which includes $3.0 billion provided through the American Recovery and Reinvestment Act. NSF funds reach all 50 states through grants to over 1,900 universities and institutions. Each year, NSF receives about 44,400 competitive requests for funding, and makes over 11,500 new funding awards. NSF also awards over $400 million in professional and service contracts yearly.

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