Wu Mengfei, Ding Lu, Sabatini Randy P, Sagar Laxmi Kishore, Bappi Golam, Paniagua-Domínguez Ramón, Sargent Edward H, Kuznetsov Arseniy I
Institute of Materials Research and Engineering, A*STAR (Agency for Science, Technology and Research), Singapore 138634, Singapore.
Department of Electrical and Computer Engineering, University of Toronto, Toronto, Ontario M5S 3G4, Canada.
Nano Lett. 2021 Nov 24;21(22):9754-9760. doi: 10.1021/acs.nanolett.1c03696. Epub 2021 Nov 15.
Colloidal quantum dots (CQDs) are a promising gain material for solution-processed, wavelength-tunable lasers, with potential application in displays, communications, and biomedical devices. In this work, we combine a CQD film with an array of nanoantennas, made of titanium dioxide cylinders, to achieve lasing via bound states in the continuum (BICs). Here, the BICs are symmetry-protected cavity modes with giant quality factors, arising from slab waveguide modes in the planar CQD film, coupled to the periodic nanoantenna array. We engineer the thickness of the CQD film and size of the nanoantennas to achieve a BIC with good spatial and spectral overlap with the CQDs, based on a second-order transverse-electric (TE)-polarized waveguide mode. We obtain room-temperature lasing with a low threshold of approximately 11 kW/cm (peak intensity) under 5-ns-pulsed optical excitation. This work sheds light on the optical modes in solution-processed, distributed-feedback lasers and highlights BICs as effective, versatile, surface-emitting lasing modes.
胶体量子点（CQDs）是用于溶液处理的波长可调谐激光器的一种很有前景的增益材料，在显示器、通信和生物医学设备中具有潜在应用。在这项工作中，我们将CQD薄膜与由二氧化钛圆柱体制成的纳米天线阵列相结合，以通过连续统中的束缚态（BICs）实现激光发射。在此，BICs是具有巨大品质因数的对称保护腔模，由平面CQD薄膜中的平板波导模产生，并与周期性纳米天线阵列耦合。我们设计CQD薄膜的厚度和纳米天线的尺寸，基于二阶横向电（TE）极化波导模，实现与CQDs具有良好空间和光谱重叠的BIC。在5纳秒脉冲光激发下，我们获得了室温激光发射，阈值低至约11千瓦/平方厘米（峰值强度）。这项工作揭示了溶液处理的分布反馈激光器中的光学模式，并突出了BICs作为有效、通用的表面发射激光模式的特点。
