High-Performance Colloidal Quantum-Dot VCSEL with Quality Factor Above 2000

Abstract

<p>Colloidal quantum-dot (CQD) vertical-cavity surface-emitting lasers (VCSELs) enable a solution-processable directional-emitting coherent light source, which is desirable for various applications, including near-eye display, sensing, and communication. However, it remains challenging to construct a controllable, high-quality VCSEL cavity without damaging the photoluminescence of CQDs to achieve the desired lasing characteristics. Here, high-quality CQDs with an engineered CdZnSe/ZnSe/ZnxCd1-xS core/interlayer/graded shell structure are developed to ensure excellent stability and sub-single-exciton gain threshold, facilitating the achievement of high-performance VCSEL. Subsequently, CQD VCSELs with distributed Bragg reflectors deposited on CQDs in situ by thermal evaporation are demonstrated. The proposed fabrication process not only enables precise control over the cavity structure but also a high cavity quality without compromising the optical properties of CQDs. Consequently, the developed CQD VCSEL exhibits a low lasing threshold of 58 µJ cm⁻² and a high lasing quality factor up to 2395, setting a record for VCSELs based on CQDs or colloidal quantum-wells. It also demonstrates stable operation for 300 h at room temperature, corresponding to 1.08 × 10⁸ stable lasing pulses, placing it among the most stable nanocrystal lasers reported. This work presents an effective strategy for achieving high-performance CQD-based VCSEL, which is significant for the future development towards non-epitaxial laser diodes.</p>