Eli Yablonovitch is renowned for his pioneering discoveries in optics and electronics. The 4n2 light trapping factor he introduced — which relates optical path length to actual thickness — is widely used to maximise solar cell efficiency. Another of Eli’s insights led to semiconductor lasers, such as those used for internet communications and DVD players, now being of the ‘strained’ type — where the atoms of the semiconductor are stretched beyond their normal separation.
By drilling cylindrical holes in a triangular array in layers of transparent material, Eli created the first three-dimensional crystal with a property known as a ‘full photonic bandgap’. This is now enabling the development of silicon photonics used in data centres. The crystal structure he created has been dubbed ‘Yablonovite’.
Eli’s work created a new field — photonic band engineering — within which he coined the term ‘photonic crystal’. His many awards for his contributions include the 2014 Rank Prize in Optoelectronics, the 2012 Harvey Prize of Israel, the IEEE 2012 Photonics Award, the IET Mountbatten Medal, and the Adolf Lomb Medal of the Optical Society.