GaAs-Based Quantum Dot Lasers

The unique optical properties of quantum dot semiconductors have brought about significant new capabilities in light-emitting devices fabricated from these materials. In particular, the performance of laser diodes based on epitaxial quantum dots grown on a GaAs substrate has been the focus of intense study for about 20 years. The advances for such lasers emitting at wavelengths longer than 1.2. μm are reviewed here. Four vital aspects are discussed, including the record-low-threshold currents and the impressive temperature stability these lasers have achieved, the extreme range of linewidth enhancement factors possible in these devices, the ultralow linewidth-power product and insensitivity to optical feedback of quantum dot distributed feedback lasers, and, finally, the progress made to date in achieving higher modulation bandwidths in directly modulated and injection-locked quantum dot lasers.