The relentless march of Moore's law is slowing as electronic circuits hit fundamental limits in speed and energy efficiency. The solution, many researchers believe, lies in photonics, using light instead of electrons to process and transmit information. But today's photonic chips rely on the same rigid, inorganic semiconductors that dominate electronics. A comprehensive new review, led by an international group of researchers, argues that the future of photonics may be grown, not fabricated.