Band edges at the high symmetry points in reciprocal space of periodic structures hold special interest in materials engineering for their high density of states. In optical metamaterials, standing waves found at these points have facilitated lasing, bound-states-in-the-continuum, and Bose–Einstein condensation. However, because high symmetry points by definition are localized, properties associated with them are limited to specific energies and wavevectors. Conversely, quasi-propagating modes along the high symmetry directions are predicted to enable similar phenomena over a continuum of energies and wavevectors. Here, quasi-propagating modes in 2D nanoparticle lattices are shown to support lasing action over a continuous range of wavelengths and symmetry-determined directions from a single device. Using lead halide perovskite nanocrystal films as gain materials, lasing is achieved from waveguide-surface lattice resonance (W-SLR) modes that can be decomposed into propagating waves along high symmetry directions, and standing waves in the orthogonal direction that provide optical feedback. The characteristics of the lasing beams are analyzed using an analytical 3D model that describes diffracted light in 2D lattices. Demonstrations of lasing across different wavelengths and lattice designs highlight how quasi-propagating modes offer possibilities to engineer chromatic multibeam emission important in hyperspectral 3D sensing, high-bandwidth Li-Fi communication, and laser projection displays.

中文翻译：

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准传播模式的激光作用

周期性结构倒易空间中高对称点的能带边缘因其高态密度而在材料工程中具有特殊的意义。在光学超材料中，在这些点发现的驻波促进了激光、连续束缚态和玻色-爱因斯坦凝聚。然而，由于定义上的高对称点是局部的，因此与它们相关的属性仅限于特定的能量和波矢量。相反，预计沿高对称方向的准传播模式可以在能量和波向量的连续体上实现类似的现象。在这里，二维纳米粒子晶格中的准传播模式被证明可以支持单个器件在连续波长范围和对称确定方向上的激光作用。使用卤化铅钙钛矿纳米晶体薄膜作为增益材料，通过波导表面晶格共振 (W-SLR) 模式实现激光发射，该模式可分解为沿高对称方向的传播波和提供光学反馈的正交方向的驻波。使用描述 2D 晶格中衍射光的分析 3D 模型分析激光束的特性。跨不同波长和晶格设计的激光演示突出了准传播模式如何为设计在高光谱 3D 传感、高带宽 Li-Fi 通信和激光投影显示器中重要的彩色多光束发射提供可能性。激光是通过波导表面晶格共振 (W-SLR) 模式实现的，该模式可以分解为沿高对称方向的传播波，以及提供光学反馈的正交方向的驻波。使用描述 2D 晶格中衍射光的分析 3D 模型分析激光束的特性。跨不同波长和晶格设计的激光演示突出了准传播模式如何为设计在高光谱 3D 传感、高带宽 Li-Fi 通信和激光投影显示器中重要的彩色多光束发射提供可能性。激光是通过波导表面晶格共振 (W-SLR) 模式实现的，该模式可以分解为沿高对称方向的传播波，以及提供光学反馈的正交方向的驻波。使用描述 2D 晶格中衍射光的分析 3D 模型分析激光束的特性。跨不同波长和晶格设计的激光演示突出了准传播模式如何为设计在高光谱 3D 传感、高带宽 Li-Fi 通信和激光投影显示器中重要的彩色多光束发射提供可能性。