John D. Joannopoulos (born April 26, 1947) is an American physicist, focused in condensed matter theory.
His doctoral studies, advised by Marvin L. Cohen, focused on electronic structure of complex crystalline and amorphous semiconductors.
[1] Joannopoulos has helped set the theoretical foundations of key computational techniques for realistic and microscopic studies of complex materials systems, including the electronic, vibrational, and optical structure of crystalline and amorphous solids, their surfaces, interfaces, and defects; localization in disordered systems; and the first ab-initio studies of phase transitions and critical phenomena.
In the early nineties, he also helped spawn the development of a new class of materials (photonic crystals) that provide new mechanisms to control the flow of light and have revolutionized the fields of optical and lightwave physics.
[citation needed] His students include Nobel Laureate Robert B. Laughlin, David Vanderbilt, Eugene J. Mele, Shanhui Fan, Steven G. Johnson, and Karin M.