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Temperature evolution of two-state lasing in microdisk lasers with InAs/InGaAs quantum dots
One-state and two-state lasing is investigated experimentally and through numerical simulation
as a function of temperature in microdisk lasers with Stranski–Krastanow InAs/InGaAs/GaAs
quantum dots. Near room temperature, the temperature-induced increment of the ground-state
threshold current density is relatively weak and can be described by a characteristic temperature
of about 150 K. At elevated temperatures, a faster (super-exponential) increase in the threshold
current density is observed. Meanwhile, the current density corresponding to the onset of two-state
lasing was found to decrease with increasing temperature, so that the interval of current density
of pure one-state lasing becomes narrower with the temperature increase. Above a certain critical
temperature, ground-state lasing completely disappears. This critical temperature drops from 107
to 37 C as the microdisk diameter decreases from 28 to 20 um. In microdisks with a diameter of
9 um, a temperature-induced jump in the lasing wavelength from the first excited-state to second
excited-state optical transition is observed. A model describing the system of rate equations and free
carrier absorption dependent on the reservoir population provides a satisfactory agreement with
experimental results. The temperature and threshold current corresponding to the quenching of
ground-state lasing can be well approximated by linear functions of saturated gain and output loss.