Fig. 1: A QD laser with an L-ITO DFB cavity.
From: Optically pumped colloidal-quantum-dot lasing in LED-like devices with an integrated optical cavity
a A proposed QLD architecture, which comprises a p-i-n multilayered QD-LED assembled on top of a DFB cavity integrated into a bottom L-ITO electrode. b A scanning electron microscopy (SEM) image of an L-ITO DFB grating with Λ = 370 nm. The scale bar is 1 µm. c Refractive indices of ITO, L-ITO and close-packed QDs as a function of wavelength. The inset shows calculated TE0 mode intensity profiles at λ = 630 nm across a device stack with a DFB resonator made of either standard ITO (left) or L-ITO (right). The red dashed and black solid lines show mode profiles for the groove and the ridge parts of the DFB grating, respectively. The greater difference between these profiles in the case of L-ITO compared to standard ITO indicates stronger optical feedback. d Surface emission spectra on the L-ITO-based device as a function of pump fluence displays a sharp transition to single-mode lasing (at λ = 630.9 nm) at w = 5.5 µJ cm−2; the inset shows emission spectra immediately before (blue) and immediately after (red) the lasing threshold. e Surface emission intensity versus pump fluence exhibits a well-pronounced threshold behavior with wlas = 5.5 µJ cm−2. The inset is a schematic of the L-ITO-based lasing device with a QD EML thickness of 200 nm. Source data are provided as a Source Data file.
