Shown here are fourteen 100-gigabit photonic integrated circuits sitting in a plastic carrier for performance testing. Credit: Emily Nathan

In his lab in Sunnyvale, CA, ­David Welch, cofounder of telecom startup Infinera, holds up a rigid two-­centimeter-wide strip featuring four patterned, gold-colored rectangles. It's made of indium phosphide, a semiconductor prized for its optical properties. The chip's simple appearance belies its complex engineering and gives little hint that it could be the key to cheaply supplying the bandwidth demanded by a YouTube-addicted world.

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