Low-threshold lasing and purcell effect in microdisk lasers at room temperature

In this paper, we discuss the Purcell effect, which enhances the spontaneous emission rate, in microdisk lasers operating at room temperature by continuous wave photopumping. We theoretically analyzed the Purcell effect at room temperature by using the four-level rate equations that include the intraband relaxation and the nonradiative effect. We also fabricated 1.55-mum GaInAsP microdisk lasers with a minimum diameter of 1.7 mum and a minimum threshold power of 19 muW. Then, we measured the carrier lifetime in a 2.6-mum-diameter device by the phase-resolved spectroscopy method, and confirmed that the carrier lifetime was shortened to 1/10 of that in the as-grown epitaxial wafer at a low pump level. From the comparison between the theory and the experiment, we estimated the Purcell factor to be 6.7, the spontaneous emission factor to be 0.11, and the nonradiative lifetime to be 4 ns. The nonradiative lifetime was consistent with that estimated by another methods. We believe that this is the first demonstration of the Purcell effect in semiconductor microcavities at room temperature.