Mode-Controlled Tapered Lasers Based on Quantum Dots

Wavelength control of tapered quantum dot (QD) lasers was achieved by adding a distributed Bragg reflector as wavelength-selective element to the devices. The Bragg wavelength of around 920 nm is matched to the gain of the single layer of InGaAs QDs that is used as active material. Devices with 1.4-mm-long tapers have reached output powers of over 1 W, and over 2 W were obtained from lasers with 3-mm-long tapers. The emission of the devices is restricted to a very narrow spectral range, with side-mode suppression ratios of over 40 dB.