Quantum dot microcavity lasers on silicon substrates

Analogous to the historical scaling of CMOS technology governed by “Moore's Law,” monolithic photonic integration on Si allows optical systems previously restricted to bulky, bench-scale apparatuses to be developed in compact form factors with small-footprint and low energy consumption. Currently, direct heteroepitaxial growth of quantum dot (QD) lasers on Si has gained strong momentum. Exceptional device performance rivals what has been achieved through heterogeneous integration. Breakthroughs in reliability rapidly progress to a point warranting discussion for near-term commercial viability. By light confinement in small volumes with resonant recirculation, microcavity lasers promise to complement the rise of Si photonics by populating these chips with small-footprint and low-threshold light sources. The dense, energetically confined, and spatially isolated QD gain medium is utilized for circumventing crystal defects in heteroepitaxy, as well as for scaling to ultra-small dimensions in microcavities. The former allows for laser growth and processing up to 450 mm Si wafer with minimal compromise in light emission efficiency, and the latter enables device miniaturization for ultra-dense photonic integration with complex functionality and economy of scale. This chapter provides an introduction to this technology, then follows with technological demonstrations of QD microcavity devices, and finally, presents an outlook of using III-V/Si epitaxy to form a bandwidth scale-up, energy scale down, volume manufacturable Si photonics solution.