Large-Scale Robust Quantum Dot Microdisk Lasers with Controlled High Quality Cavity Modes

This study reports a facile on-chip fabrication of CdSe/Cd_{1− x}Zn_xSe_{1− y}S_y quantum dot microdisk lasers and their large-area arrays via a pattern-assisted layer-by-layer assembly process. This approach combines the versatility of colloidal semiconducting nanoparticles (bright emission, solubility, and high stability) with the spatial precision of optical lithography to create robust large-area optical lasing arrays (up to a few thousand disks). Specifically, microdisk lasers with high quality factors (within 1000–2000) are fabricated with predefined size and shape (as controlled by master templates) with high consistency and throughput, essentially providing a new approach to fabricate difficult-to-control on-chip optical cavities in a low-cost and effective manner. Notably, the number of longitudinal cavity modes in the microdisk laser can be precisely controlled by varying the microdisks' diameter, allowing for either near-single mode or multimode operation while preserving high quality factors. Furthermore, the cross-linking of quantum dots imparts high chemical resistance and mechanical robustness that helps retain the structural integrity under harsh processing conditions (such as sonication or direct exposure to various solvents). As such, these quantum dot microdisk laser arrays are promising candidates for advancing the development of large-area, low-cost on-chip photonic structures with controlled lasing modes.