Eli Yablonovitch: Father of photonic band engineering

Eli Yablonovitch, professor of electrical engineering and computer sciences, is renowned for his pioneering discoveries in optics and electronics. He famously introduced the 4 (n squared) factor as the theoretical limit for light trapping photovoltaics. Sometimes referred to as the “Yablonovitch limit,” this factor is used for almost all commercial solar panels worldwide. In fact, a company he co-founded, Alta Devices, holds the world record for solar cell efficiency — 28.8 percent.

But he is best known for coining the term “photonic crystal” and creating the first three-dimensional photonic crystal with full photonic bandgap, which essentially blocks certain wavelengths of light from passing. This crystal is now known as “Yablonovite,” and his groundbreaking work created the field of photonic band engineering. Today, photonic crystals are an essential component of many technologies, like optical fibers for telecommunications or to increase the efficiency of light emitting diodes. These crystals are also used to help direct infrared laser beams that destroy tumors in cancer surgery.

A native of Austria, Yablonovitch spent decades in industry — at Exxon Research Center and Bell Communications Research — before returning to academia. In 2007, he joined the Berkeley Engineering faculty and now directs the $50 million National Science Foundation Center for Energy Efficient Electronics on campus.

In recognition of his achievements, Yablonovitch has been honored with many high-profile awards, including the Isaac Newton Medal and Franklin Medal. He is also an elected member of the National Academy of Engineering and the National Academy of Sciences, among many other notable academies.

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