基于带隙反馈与局域表面等离子体共振耦合多手段调控随机激光的研究

Random lasers have attracted widen attentions in the speckle-free full-field imaging as a new type of light source. The random lasers do not need the resonant cavity feedback, which greatly simplifies laser design, however, it results in the deficiency for controlling random lasers. In the project, we will control the random lasers emission, such as wavelength, handedness, polarization, and coherence degree based on the coupling effect between the band gap feedback of cholesteric liquid crystal (CLC) and localized surface plasmon resonance (LSPR) of the metal nanoparticles (NPs) in the metal NPs doped-gain CLC. The strong scattering of metal NPs induces defect in one-dimensional photonic crystal of CLC and boosts the random lasing. Moreover, the LSPR of metal NPs selectively enhances the photoluminescence emission, which will decreases the threshold and tunes the wavelength of random laser in the defect CLC. The reflection wavelength and handedness of light traveling the CLC have been controlled by external control method, such as electric field, optic field, temperature, handedness and concentration of chiral dopants, and then that of random lasers will be tuned. The modulation of the coherence degree of the random lasers on external control method is studied. And we exploit the application of speckle-free full-field imaging in the visible light. In addition, we investigate the regularity and principle to control CLC random lasers based on the coupling effect between the band gap feedback of CLC and LSPR of the metal NPs using multi-tunable methods. These studies will provide scientific and technical evidences and pave a way to control random lasers.

随机激光作为一种新型光源在无散斑成像领域受到广泛关注。随机激光不需要谐振腔作为反馈机制，一方面简化了他的结构，同时导致随机激光调控的匮乏。本项目拟在增益胆甾型液晶（CLC）体系掺杂金属纳米颗粒利用CLC带隙反馈与金属纳米颗粒局域表面等离子体共振（LSPR）耦合效应共同增强和调控随机激光性能：波长、旋光性、偏振及相干性。利用金属纳米颗粒强散射效应造成CLC一维光子晶体的缺陷，促进CLC体系发射随机激光，同时金属纳米颗粒LSPR效应选择性增强荧光发射，从而降低缺陷CLC随机激光阈值及调控随机激光波长。通过电光热以及手型掺杂剂的含量与手型控制CLC带隙反射波长及旋光性，从而调控CLC随机激光的波长及旋光性。研究多调控手段下CLC随机激光相干性及开展可见光范围内对无散斑成像应用。探索多手段调控CLC带隙反馈及金属纳米颗粒LSPR耦合对CLC随机激光控制的规律和机理，为提高随机激光控制提供科学依据。

随机激光作为一种新型光源在无散斑成像领域受到广泛关注。随机激光不需要谐振腔作为 反馈机制，一方面简化了他的结构，同时导致随机激光调控的匮乏。本项目在增益胆甾型液晶（CLC）体系掺杂金属纳米颗粒利用CLC带隙反馈与金属纳米颗粒局域表面等离子体共振（LSPR）耦合效应共同增强和调控随机激光性能：波长、旋光性、偏振及相干性。主要研究内容、重要结果和关键数据包括：一是研究了CLC带隙反馈与金属纳米颗粒的LSPR的耦合共同增强及大范围调控随机激光的波长、阈值、空间相干性。实现了等离子体共振效应增强能量转移长波段随机激光强度，随机激光强度增强 200倍，进一步利用电光热效应调控金属纳米颗粒掺杂CLC体系随机激光的空间相干性，利用波长与空间相干性可调谐CLC随机激光作为新型光源开展在可见光范围（黄色-红色）无散斑抑制成像领域应用；二是通过电场、温度大范围调控CLC的带隙，从而调控其反射波长，进而调控CLC随机激光的波长，调控波长达110 nm。实现多手段大范围可调谐随机激光光源，为它应用于激光物理及散斑抑制成像提供原理和技术支撑；三是研究了液晶波导结构实现液晶随机激光的偏振调控；四是从统计动力学研究了随机激光的副本对称破缺现象。本项目的研究为提高随机激光控制提供科学依据和技术支撑。