Integrated photonics has profoundly affected a wide range of technologies
underpinning modern society. The ability to fabricate a complete optical system on
a chip offers unrivalled scalability, weight, cost and power efficiency. Over the last
decade, the progression from pure III–V materials platforms to silicon photonics has
significantly broadened the scope of integrated photonics, by combining integrated
lasers with the high-volume, advanced fabrication capabilities of the commercial
electronics industry. Yet, despite remarkable manufacturing advantages, reliance
on silicon-based waveguides currently limits the spectral window available to
photonic integrated circuits (PICs). Here, we present a new generation of integrated
photonics by directly uniting III–V materials with silicon nitride waveguides on Si
wafers. Using this technology, we present a fully integrated PIC at photon energies
greater than the bandgap of silicon, demonstrating essential photonic building
blocks, including lasers, amplifiers, photodetectors, modulators and passives,
all operating at sub-micrometre wavelengths. Using this platform, we achieve
unprecedented coherence and tunability in an integrated laser at short wavelength.
Furthermore, by making use of this higher photon energy, we demonstrate superb
high-temperature performance and kHz-level fundamental linewidths at elevated
temperatures. Given the many potential applications at short wavelengths, the
success of this integration strategy unlocks a broad range of new integrated photonics
applications.