University of Rochester Institute of Optics professor Chunlei Guo uses a source of simulated sunlight to test the absorption of a solar thermoelectric generator created in his lab in Wilmot Building May 30, 2025. Guo has developed a technique that uses femtosecond lasers to etch nanostructures onto metal surfaces that enhance solar absorption but minimize infrared emissions to create highly efficient solar thermoelectric generators. // photo by J. Adam Fenster / University of Rochester