Optically pumped rolled-up InGaAs/GaAs quantum dot microtube lasers.

The authors report on the achievement of lasing in rolled-up semiconductor microtubes at room temperature, wherein self-organized InGaAs/GaAs quantum dots are incorporated as the gain medium. The free-standing quantum dot microtubes, with a diameter of approximately 5-6 microm and wall thickness of approximately 100 nm, are formed when the coherently strained InGaAs/GaAs quantum dot heterostructure is selectively released from the GaAs substrate. The devices are characterized by an ultralow threshold (approximately 4 microW) and a minimum intrinsic linewidth of approximately 0.2 - 0.3 nm at room temperature. The multiple lasing modes are analyzed using both the finite-difference time domain method and also a planar dielectric waveguide model.