John D. Joannopoulos

John D. Joannopoulos is a physicist and engineer known for his work on the electronic properties of materials, particularly in understanding how light and electrons behave in complex structures. He specializes in photonic and phononic crystals—materials engineered to control the flow of light and sound—much like how semiconductors control electricity. His research helps develop advanced technologies such as more efficient lasers, optical fibers, and sensors. As a professor at MIT, he combines theoretical insights with practical applications, contributing significantly to the fields of nanophotonics and material science.