A multinational team has published a paper that suggests aerogels could be used as tunable waveplates “in a broad spectral range.”
Pradeep Bhupathi, Rodica M. Martin, Lukas Jaworski, David B. Tanner and Yoonseok Lee from the University of Florida (Gainesville, Fla.), Jungseek Hwang from the Pusan National University (Busan, Republic of Korea), Jackson Blankstein from the Alexander W. Dreyfoos School of the Arts (West Palm Beach, Fla.) and Norbert Mulders from the University of Delaware (Newark, Del.) in the current edition of Optics Express.
The team conducted their measurements while putting silica aerogel under varying degrees of uniaxial compression. They found that the compressed aerogels displayed a great deal of bifringence (double refraction) that was roughly proportional to the amount of strain placed on the material. They also found the bifringence was reversible through repeated compression-decompression cycles.
The bifringence properties in a material are useful for making waveplates – materials that alter the polarization of light. Thus, aerogels could be used to dynamically affect light polarization by simply varying the amount of compression on the material.
The authors write that the material could replace a 150-year-old device that is still used in physics labs and microscopy to adjust for and measure elliptically plane-polarized light, the Babinet compensator. “Aerogel waveplates might have certain advantages compared to the Babinet compensator: uniform phase retardation in the whole device, low (even first) order waveplates, easy calibration, and multiple adjustable parameters (thickness, compression rate, and porosity),” the authors note in their summary.