Lasing at a wavelength close to 1.3 μm in InAs quantum-dot structures

The feasibility of lasing at a wavelength close to 1.3 mu m is demonstrated in InAs quantum-dot structures placed in an external InGaAs/GaAs quantum well. It is shown that the required wavelength can be attained with the proper choice of thickness of the InAs layer deposited to form an array of three-dimensional islands and with a proper choice of mole fraction of InAs in the InGaAs quantum well. Since the gain attained in the ground state is insufficient, lasing is implemented through excited states in the temperature interval from 85 K to 300 K in a structure based on a single layer of quantum dots. The maximum attainable gain in the laser structure can be raised by using three rows of quantum dots, and this configuration, in turn, leads to low-threshold (70 A/cm(2)) lasing through the ground state at a wavelength of 1.26 mu m at room temperature. (C) 1999 American Institute of Physics. [S1063-7826(99)02808-2].