Abstract
Quantum dot microlasers, as multifunctional optical source components, are of great importance for full-color high-pixel display, miniaturized coherent lighting, and on-chip integrated photonic and electronic circuits. Since the first synthesis of colloidal quantum dots (CQD) in the 1990s, motivation to realize high-performance low-cost CQD micro-/nanolasers has been a driving force for more than three decades. However, the low packing density, inefficient coupling of CQDs with optical cavities, and the poor thermal stability of miniaturized complex systems make it challenging to achieve practical CQD micro-/nanolasers, especially to combine the continuous working ability at high temperatures and the low-cost potential with mass-produced synthesis technologies. Herein, we developed close-packed CQD-assembled microspheres and embedded them in a silica matrix through the rapid self-aggregation and solidification of CdSe/ZnS CQD. This technology addresses the core issues of photoluminescence (PL) quenching effect and low optical gain in traditional CQD laser research. High-efficiency low-threshold CQD microlasers are demonstrated together with long-playing (40 min) working stability even at 450 K under pulsed laser excitation, which is the highest operational temperature for CQD lasers. Moreover, single-mode CQD microlasers are obtained with tunable wavelengths across the entire visible spectral range. The chemosynthesis process supports the mass-produced potential of high-density integrated CQD microlasers, promoting CQD-based low-cost high-temperature microdevices.
Highlights
Low-dimensional colloidal quantum dots (CQD) have attracted significant attention because of their unique structures, extraordinary optical properties, and low-cost preparation processes[1,2,3,4,5,6,7,8,9,10,11]
We developed a novel assembly technique combined with the sol–gel method to fabricate CdSe/ZnS CQD-assembled microspheres (CQDAMs) solidified in a silica matrix, which guarantees that the CQDAMs work stably at high temperatures and solves the problems of gain packing density and coupling efficiency
Methods for realizing CQD lasers require an external cavity structure, and this can be roughly divided into two categories
Summary
Low-dimensional CQD have attracted significant attention because of their unique structures, extraordinary optical properties, and low-cost preparation processes[1,2,3,4,5,6,7,8,9,10,11]. Solidified monodisperse CQD in the protective matrix can eliminate the surface defect states and improve the temperature tolerance of CQD32,33, they still suffer from low gain density and inefficient coupling in current CQD laser research To address these issues, we developed a novel assembly technique combined with the sol–gel method to fabricate CdSe/ZnS CQD-assembled microspheres (CQDAMs) solidified in a silica matrix, which guarantees that the CQDAMs work stably at high temperatures and solves the problems of gain packing density and coupling efficiency. We first achieved single-mode lasing based on solidified CQDAMs with operative temperatures up to 450 K This is the highest operational temperature for CQD microlasers. The solution-processable method has the advantages of low cost and potential for mass production It does not require complex optical cavity processing, which means no expensive equipment or extremely complex processing is required. These CQDAMs lasers can be highly integrated into a microsubstrate, and applicable to other kinds of semiconductor nanoparticles, which promote predictable commercial application value in high-temperature lowcost micro-integrated optoelectronic devices
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