Eli Yablonovitch (born 15 December 1946) is an American physicist and engineer who, along with Sajeev John founded the field of photonic crystals in 1987.He and his team were the first to create a 3-dimensional structure that exhibited a full photonic bandgap, it is called Yablonovite. In addition to pioneering photonic crystals, he was the first to recognize that a strained quantum-well laser has a significantly reduced threshold current compared to its unstrained counterpart. This technique is now applied to the majority of semiconductor lasers fabricated throughout the world.He received Isaac Newton Medal in 2015 for his visionary and foundational contributions to photonic nanostructures.