In the past two decades, great efforts have been made to achieve colloidal quantum dots (CQDs)-based lasers, especially CQD-based single-mode lasers, which is important in on-chip optical processing and data storage due to low noise and good monochromaticity.

Although there are concrete demonstrations of solution-processed CQDs films enabled optical microcavities, the radiation collected from the samples exhibits random lasing, or multi-mode lasing due to low coupling efficiency, low quality factor, and it's often difficult to control laser mode. Thus, CQDs based single-mode lasers across the whole visible spectral range haven't been achieved yet.

A research team from the Shanghai Institute of Optics and Fine Mechanics has recently demonstrated perovskite CQDs single-mode laser with good performance across the entire visible spectra range. The work was published in the Journal of Materials Chemistry C.

In this study, a composited microcavity was obtained through the conformal deposition of cesium lead halide perovskite (LHP) CQDs on a high quality individual sub-micron ZnO rod by dip-coating self-assembled techniques. A single-mode lasing with high quality factor and low threshold was obtained.

By tuning the size of ZnO microrods, size of CQDs, and the elements of CQDs, broad-band tunable single-mode lasers can be achieved in the whole visible spectra region.

Experiments, together with theoretical studies, analyzed the physical mechanism and output performance of QDs laser and proposed that the efficient coupling between CQDs and microcavity is key to efficient and high-quality lasing.

This work was supported by the National Natural Science Foundation of China and the Youth Top-notch Talent Support Program in Shanghai.

Broad-band CQDs single-mode lasers in CQDs/ZnO composited microcavity. (Image by SIOM)