Transient behaviors of optically pumped InGaAs quantum-dot microdisk lasers
Date Issued
2012
Date
2012
Author(s)
Shen, Yu-Chih
Abstract
Microdisk lasers have attracted much attention due to their high quality factors and small mode volumes. Therefore, optical modes can be highly confined in the microdisk cavities. These two factors result in ultralow lasing threshold and large spontaneous emission factor, which provides potential applications for microdisk lasers in photonic integrated circuits. Large Purcell factors of microdisk lasers induce strong enhancement of spontaneous emission and small carrier lifetime, which causes fast modulation speed of microdisk lasers.
In this thesis, we fabricated InGaAs quantum-dot microdisk lasers in several sizes with the smallest disk size down to 1.55 μm in diameter. The lasing threshold reduces down to 10 μW under pulse excitation at 80 K. The mode shifts were measured from 80 K to 200 K and their values are about 0.5Å/K. The transient behaviors of microdisk lasers show fast turn-on time of 200 ps without occurrence of relaxation oscillations. From the double-exponential function fitting of time-resolved photoluminescence decay curves, the enhancement of the spontaneous emission factor is about 6 for a 4-μm-diameter microdisk laser.
Subjects
quantum dot
microdisk laser
time-resolved measurement
Purcell effect
Type
thesis
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