基于多形貌银纳米颗粒的多波长相干随机激光研究

采用溶剂热法分别制备了球形银纳米颗粒和多形貌银纳米颗粒，其中球形银纳米颗粒具有400 nm的窄带等离激元共振峰，而多形貌银纳米颗粒的共振区间在400～700 nm之间，将它们分别掺入R6G与PVP的混合溶液中，利用旋涂法在玻璃基板上制备银纳米颗粒嵌入染料掺杂聚合物薄膜随机激光器。采用纳秒脉冲激光进行随机激光泵浦实验，实验结果表明球形银纳米颗粒染料掺杂聚合物薄膜只有自发辐射峰，而多形貌银纳米颗粒染料掺杂聚合物薄膜具有线宽<0.8 nm的相干随机激光发射光谱，其阈值为1.9 mJ·cm-2, 这可能是由于银纳米颗粒的等离激元共振区间与R6G的发射光谱重叠，支持局域等离激元效应的形成，明显的局域场增强有效地改善了与附近分子的相互作用，从而激发了更多的辐射光子，促进了高增益的形成。进一步，利用多形貌银纳米颗粒在银纳米颗粒染料掺杂聚合物薄膜中随机分布的特性，通过改变泵浦位置，实现了20 nm范围内的随机激光输出波长的调控，具体输出范围为590.1～610.4 nm。认为这是由于多形貌银纳米颗粒在不同位置的组成和分布不同，改变了表面等离激元的相互作用和光子的散射能力，从而形成不同的增益效应和不同的封闭光振荡路径。此外，考虑到多形貌银纳米颗粒的共振波长较宽，探究了其用于输出其他颜色光的可能性。以与上述银纳米颗粒R6G染料掺杂聚合物薄膜相似的制备方法，制备了多形貌银纳米颗粒掺杂DCJTB染料聚合物薄膜，并且进行随机激光泵浦实验。结果表明，可以有效的产生波长为675 nm，半高宽<0.8 nm的相干红光随机激光，并且阈值仅为0.98 mJ·cm-2。研究结果在宽带可调谐随机激光器研究以及多色随机激光器研究领域具有重要的参考价值。

Multi-Wavelength Random Lasing Form Doped Polymer Film With Embedded Multi-Shaped Silver Nanoparticle

In this paper,spherical silver nanoparticles and multi-shaped silver nanoparticle were synthesized using the facile solvothermal method.The spherical silver nanoparticle has a narrow single LSPR_peak around 400 nm,and a multi-shaped silver nanoparticles resonance region between 400~700 nm.A random laser was achieved in doped polymer film embedded multi-shaped silver nanoparticleson glass.It is experimentally shown that the spherical silver nanoparticles doped polymer film only has spontaneous emission peak,and dye doped polymer film with morphology of silver nanoparticles has a line width of 0.5 nm coherent random laser emission.The threshold is 1.9 mJ·cm^-2.Due to multi-shaped silver nanoparticles exhibiting multiple plasmon resonances,spectrally overlapping with the emission of R6G,improving interactions with nearby molecules to stimulate more emission,which is beneficial to the formation of high gain.Further,by changing the pump position,the random lasing emission can be tuned in the range of 20 nm,wavelength ranging from 590.1 to 610.4 nm.It is likely the composition and distribution of silver nanoparticles at different locations are distinct,which change the interaction of surface plasmonic and the scattering ability of photons,leading to different gain effects and distinct closed optical oscillating paths.In addition,considering that multi-shaped silver nanoparticles have a broad localized surface plasmonic resonance region,we investigated whether multi-shaped silver nanoparticles can be used to achieve red random laser.Under the same preparation method,we embedded it into a polymer film doped with DCJTB.The results show that the coherent read coherent random lasing with a wavelength of 675 nm can be generated effectively,and the threshold value is only 0.98 mJ·cm^-2.The results of this work are a great reference value in the research of wideband tunable random laser and random multicolor laser.