With unprecedented ability to localize electromagnetic field in time and space, the nanometer scale laser promises exceptionally broad scientific and technological innovation. However, as the laser cavity becomes subwavelength, the diffraction of light prohibits the directional emission, so-called the directionality, one of the fundamental attributes of the laser. Here, we have demonstrated a d...

• Demonstration of an enhancement in the modulation bandwidth from 16 GHz to 28 GHz in an injection locked semiconductor laser with a coincident reduction in parasitic chirp. • Demonstration of room-temperature, continuous-wave operation of the first bipolar cascade laser. This laser demonstrated an internal efficiency of 150% and a measured external modulation efficiency of 99.3%. Continuous-w...

More and more applications require semiconductor lasers distinguished not only by large modulation bandwidths or high output powers, but also small spectral linewidths. The theoretical understanding of the root causes limiting linewidth is therefore great practical relevance. In this paper, we derive a general expression for calculation step in self-contained manner. We build on theory develope...