Fig. 3: Effect of mode confinement factor on lasing.
From: Optically pumped colloidal-quantum-dot lasing in LED-like devices with an integrated optical cavity
a In type-A (top) and type-B (bottom) devices, the mode confinement factor is tuned by varying, respectively, the thickness of the QD active region (HQD = 50–300 nm) or the top TCTA layer (HTCTA = 50–500 nm; HQD is fixed at 100 nm). b Lasing threshold versus ΓQD for type-A (red) and type-B (green) devices. A type-A device with HQD = 50 nm does not lase due to the lack of a supported waveguided mode. However, lasing restores (magenta data point) upon addition of a 60-nm TCTA layer, which helps recover the device waveguiding properties. A type-A device with HQD = 50 nm and an additional 60-nm TCTA layer and a type-B device with HQD = 100 nm and HTCTA = 500 nm have ΓQD of 18.5% and 13.5%, respectively; these values fall within the range of ΓQD of typical QD-LEDs (Supplementary Fig. 5). c A pump-intensity-dependent emission intensity of a type-A device with HQD = 50 nm and HTCTA = 60 nm (displayed in the inset). Despite an ultrathin QD gain region and a correspondingly low ΓQD (=18.5%), the device exhibits a fairly low lasing threshold of 18.8 µJ cm−2. d The device shows a clear single-mode lasing behavior above the lasing threshold (w = 1.2wlas = 22.6 µJ cm−2) with a lasing wavelength of 624.6 nm. Source data are provided as a Source Data file.
