In a major breakthrough for optoelectronics, researchers at Columbia University have made the smallest yet integrated photonic circuit. In the process, they have managed to attain a high level of performance over a broad wavelength range, something not previously achieved. The researchers believe their discovery is equivalent to replacing vacuum tubes in computers with semiconductor transistors—something with the potential to completely transform optical communications and optical signal processing. The research community has been feverishly trying to build i ntegrated photonic circuits that can be shrunk to the size of integrated circuits (ICs) used in computer chips. But there’s a big problem: When you use wavelengths of light instead of electrons to transmit information, you simply can’t compress the wavelengths enough to work in these smaller chip-scale dimensions. In research described in the journal Nature Nanotechnology , the integrated ...