近日，南方科技大学的王恺与香港大学的Hoi Wai Choi等人合作并取得一项新进展。他们实现了低阈值表面发射胶体量子点圆形布拉格激光阵列。相关研究成果已于2025年1月7日在国际知名学术期刊《光：科学与应用》上发表。

该研究团队研发了具有核/中间层/渐变壳结构的高质量胶体量子点（CQD）材料，以实现低增益阈值和高稳定性。随后，研究人员成功制备了基于胶体量子点集成圆形布拉格谐振器（CBR）的表面发射激光器。得益于CBR的强场约束效应，该激光器实现了近单位模式限制因子（Γ达89%）和高达22.7的普塞尔因子，从而使得激光阈值低至17μJ/cm²，相比胶体量子点垂直腔表面发射激光器的阈值（56μJ/cm²）降低了70%。

得益于高质量的胶体量子点材料和激光腔设计，该胶体量子点CBR激光器能在室温下连续稳定运行1000小时（相当于3.63×10⁸个脉冲）。这一性能在溶液法制备的纳米晶体激光器中堪称最佳。此外，CBR的小型化模式体积使得胶体量子点激光器的集成密度达到前所未有的高度，超过2100像素/英寸。总体而言，该研究提出的低阈值、稳定且紧凑集成的胶体量子点CBR激光器阵列将推动胶体量子点激光器在实际应用中的发展。

据悉，胶体量子点（CQDs）因其波长可调性和低光学增益阈值的特性，成为极具吸引力的增益介质。因此，胶体量子点激光器，尤其是表面发射型激光器，在显示、传感和通信领域展现出巨大潜力。然而，要实现具有高稳定性和高集成密度的，低阈值表面发射胶体量子点激光器阵列仍面临挑战。为此，必须将胶体量子点材料的改进与激光腔的设计优化相结合。

附：英文原文

Title: Low-threshold surface-emitting colloidal quantum-dot circular Bragg laser array

Author: Tan, Yangzhi, Huang, Yitong, Wu, Dan, Wang, Yunjun, Sun, Xiao Wei, Choi, Hoi Wai, Wang, Kai

Issue&Volume: 2025-01-07

Abstract: Colloidal quantum dots (CQDs) are attractive gain media due to their wavelength-tunability and low optical gain threshold. Consequently, CQD lasers, especially the surface-emitting ones, are promising candidates for display, sensing and communication. However, it remains challenging to achieve a low-threshold surface-emitting CQD laser array with high stability and integration density. For this purpose, it is necessary to combine the improvement of CQD material and laser cavity. Here, we have developed high-quality CQD material with core/interlayer/graded shell structure to achieve a low gain threshold and high stability. Subsequently, surface-emitting lasers based on CQD-integrated circular Bragg resonator (CBR) have been achieved, wherein the near-unity mode confinement factor (Γ of 89%) and high Purcell factor of 22.7 attributed to the strong field confinement of CBR enable a low lasing threshold of 17μJcm^-2, which is 70% lower than that (56μJcm^-2) of CQD vertical-cavity surface-emitting laser. Benefiting from the high quality of CQD material and laser cavity, the CQD CBR laser is capable of continuous stable operation for 1000hours (corresponding to 3.63×10⁸ pulses) at room temperature. This performance is the best among solution-processed lasers composed of nanocrystals. Moreover, the miniaturized mode volume in CBR allows the integration of CQD lasers with an unprecedentedly high density above 2100 pixels per inch. Overall, the proposed low-threshold, stable and compactly integrated CQD CBR laser array would advance the development of CQD laser for practical applications.

DOI: 10.1038/s41377-024-01714-9

Source: https://www.nature.com/articles/s41377-024-01714-9