Room-temperature lasing in a single nanowire with quantum dots

Semiconductor nanowire lasers are promising as ultrasmall, highly efficient coherent light emitters in the fields of nano-photonics, nano-optics and nanobiotechnology(1,2). Although there have been several demonstrations of nanowire lasers using homogeneous bulk gainmaterials(3-14) or multi-quantum-wells/disks(15-17), it is crucial to incorporate lower-dimensional quantum nano-structures into the nanowire to achieve superior device performance in relation to threshold current, differential gain, modulation bandwidth and temperature sensitivity. The quantum dot is a useful and essential that can meet these requirements(18). However, difficulties in forming stacks of quantum dots in a single nanowire hamper the realization of lasing operation. Here, we demonstrate room-temperature lasing of a single nanowire containing 50 quantum dots by properly designing the nanowire cavity and tailoring the emission energy of each dot to enhance the optical gain. Our demonstration paves the way toward ultrasmall lasers with extremely low power consumption for integrated photonic systems.