Eli Yablonovitch

James & Katherine Lau Professor of Engineering; Director, National Science Foundation Center for Energy Efficient Electronics Science. Father of photonic bandgaps. Coined the term photonic crystal, proposing the idea in a 1987 paper (also proposed, independently, by Sajeev John two months later). First to discover pitfalls in photonic bandgap design (1989) and to demonstrate a successful photonic bandgap structure experimentally (1991). Proposed the concept of donor and acceptor doping of a photonic crystal, which has led to much of the current band structure engineering.

Introduced the idea that strained semiconductor lasers could have superior performance due to reduced valence band (hole) effective mass, a concept that is now almost universally used in semiconductor lasers, particularly telecommunications lasers, and employed in practically every human interaction with the internet, in DVD lasers, and in laser pointers.

Photovoltaic research beginning at Exxon identified principles for enhancing efficiency and introduced the 4n^2 light-trapping factor that is now used commercially in almost all high-performance solar cells.  His mantra "A great solar cell has to be a great LED" broke all the efficiency records in solar cells. 

Founder of Ethertronics Inc., that has shipped >10^9 cellphone antennas, and Luxtera Inc., the pioneer in Silicon Photonics.