Optical loss and lasing characteristics of high-quality-factor AlGaAs microdisk resonators with embedded quantum dots

Abstract

Optical characterization of AlGaAs microdisk resonant cavities with a quantum dot active region is presented. Direct passive measurement of the optical loss within AlGaAs microdisk resonant structures embedded with InAs/InGaAs dots-in-a-well (DWELL) is performed using an optical-fiber-based probing technique at a wavelength (λ ~ 1.4 μm) that is red detuned from the dot emission wavelength (λ ~ 1.2 μm). Measurements in the 1.4 μm wavelength band on microdisks of diameter D=4.5 μm show that these structures support modes with cold-cavity quality factors as high as 3.6 x 10^(5). DWELL-containing microdisks are then studied through optical pumping at room temperature. Pulsed lasing at λ ~ 1.2 μm is seen for cavities containing a single layer of InAs dots, with threshold values of ~ 17 μW, approaching the estimated material transparency level. Room-temperature continuous-wave operation is also observed.