Quantum Dot Lasers

Abstract

For axial collimated lasers, quantum dot lasers (QDLs) represent a significant breakthrough for the technology of semiconductor lasers as they have superior characteristics to bulk and quantum lasers. By virtue of their nanoscale size, and three-dimensional quantum confinement, these structures also have discrete energy levels, manifesting as lower threshold currents, higher stability at high temperatures, and higher modulation bandwidths. We first discuss the underlying principles that govern the performance of QDL, which include quantum confinement and carrier dynamics, followed by specific materials and fabrication processes such as molecular beam epitaxy, and metal-organic chemical vapor deposition. In addition, we review some latest advancement made in the field, such as the introduction of electrically pumped QDLs and mode-locked devices, as well as the easy interfacing of QDLs with silicon photonics systems. We present several key fields of application, namely optical communications, biomedical diagnostics and the emerging sphere of quantum technologies. We then discuss some of the on-going challenges, primarily uniformity and scalability, and identify possible future developments and commercial opportunities for QDLs. The purpose of such an in-depth review is to provide a simplified resource for scientists and engineers working on development of the next generation optoelectronics.