Nanoshell whispering galleries improve thin solar panels

This scanning electron microscope image shows a cross section of a layer of hollow nanoshells made of photovoltaic silicon. The thin spherical structure improves light absorption by trapping the light inside the material, creating what are known as optical whispering galleries. Credit: Yan Yao

Visitors to Statuary Hall in the U.S. Capitol Building may have experienced a curious acoustic feature that allows a person to whisper softly at one side of the cavernous, half-domed room and for another on the other side to hear every syllable. Sound is whisked around the semi-circular perimeter of the room almost without flaw. The phenomenon is known as a whispering gallery.