Characteristics of the ground-state lasing operation in V-groove quantum-wire lasers

Lasing from the ground subband transition, which has long been attempted in one-dimensional (1-D) structures, has been achieved for the first time with vertically stacked, AlGaAs-GaAs multiple quantum-wire (QWR) lasers, fabricated by flow-rate modulation epitaxy on V-groove substrates. Direct experimental evidence is provided by the consistency of the photon energies of the lasing and photoluminescence peaks, in the temperature range 4.5 K-300 K. It is further ensured by numerical calculation of the electronic subband energy states with the corresponding QWR structure. The lasers with cavity lengths of 350 /spl mu/m, show fundamental transverse mode, typical threshold current of 5 mA, an internal quantum efficiency of 18.5%, ultrahigh characteristic temperature T/sub 0//spl sim/322 K above room temperature, and remarkably low wavelength-tuning rates of current (<0.012 nm/mA) and temperature (<0.19 nm//spl deg/C). Ultrafast lasing behaviors at the ground (n=1) and the second (n=2) transition of the QWR are also investigated in terms of the gain-switching method, using a characteristic of the wavelength shift from the n=1 to the n=2 subband with shortening the cavity length.