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

摘要

Lasing from the ground subband transition, which has long beennattempted in one-dimensional (1-D) structures, has been achieved for thenfirst time with vertically stacked, AlGaAs-GaAs multiple quantum-wiren(QWR) lasers, fabricated by flow-rate modulation epitaxy on V-groovensubstrates. Direct experimental evidence is provided by the consistencynof the photon energies of the lasing and photoluminescence peaks, in thentemperature range 4.5 K-300 K. It is further ensured by numericalncalculation of the electronic subband energy states with thencorresponding QWR structure. The lasers with cavity lengths of 350nΜm, show fundamental transverse mode, typical threshold current of 5nmA, an internal quantum efficiency of 18.5%, ultrahigh characteristicntemperature T0~322 K above room temperature, and remarkablynlow wavelength-tuning rates of current (<0.012 nm/mA) and temperaturen(<0.19 nm/°C). Ultrafast lasing behaviors at the ground (n=1) andnthe second (n=2) transition of the QWR are also investigated in terms ofnthe gain-switching method, using a characteristic of the wavelengthnshift from the n=1 to the n=2 subband with shortening the cavity length