Light confinement and nanolasers using metal-dielectric nanostructures

我们探索了隐藏在随机介质和等离子体之间的跨学科前沿的新的物理和光学功能。实验证明了在金属组成的随机激光介质中，通过操纵表面等离子体与光子之间的耦合来裁剪激光共振特性的能力。介质的核心。壳纳米粒子和有机染料。它揭示了核心。如果散射强度足够弱，基于壳纳米粒子的系统表现出与含有纯金属纳米粒子的系统不同的光学反馈特征。泵浦阈值随壳体厚度的增加而增加，这可以直接证明局部场增强在相干反馈的出现中起着核心作用。从接近金属表面的荧光团的荧光特性的改变角度讨论了阈值和光反馈中的异常行为。我们制备了由各向同性金属纳米粒子核和各向异性非晶氧化物壳组成的光学双折射材料。样品显示出波长选择性增强的光学双折射。采用斜向沉积技术在纳米银表面沉积非晶氧化铁薄膜。这就产生了围绕着纳米银粒子的非晶态氧化铁的椭球壳。由于壳的各向异性，形成双折射；平行于椭球延伸方向的偏振光折射率与垂直偏振光折射率不同。此外，在局域表面等离子体共振（LSPR）波长附近，偏振面旋转明显增强。两个光轴之间的折射率差可达0。在600纳米的光线下，这是典型的双折射晶体方解石的两倍多。14为可见光)。推测各向异性壳层诱导了LSPR波长对入射光偏振方向的依赖，从而通过Kramers-Kronig关系导致了折射率的偏振依赖。少

We have explored novel physics and optical functionalities hidden in the inter-discipline frontier between random media and plasmonics.We experimentally demonstrate the capability of tailoring lasing resonance properties by manipulating the coupling between surface plasmons and photons in random lasing media composed of metallic. dielectric core. shell nanoparticles and organic dyes. It is revealed that core. shell nanoparticle-based systems exhibit optical feedback features distinctive from those containing pure metallic nanoparticles, provided that the scattering strength is weak enough. The pump threshold increases with an increment in the shell thickness, which can provide a direct proof that the local field enhancement plays a central role in the emergence of coherent feedback. The anomalous behavior in both threshold and optical feedback is discussed in terms of the modification of fluorescent properties of fluorophores close to metallic surface.We have prepared optically birefri … More ngence materials consisting of an isotropic core of metal nanoparticle and an anisotropic shell of amorphous oxide. The sample shows an enhanced optical birefringence in a wavelength-selective way. The sample was prepared by depositing amorphous iron oxide thin films on top of the silver nanoparticles using the oblique deposition technique. This results in ellipsoidal shell of amorphous iron oxide surrounding a silver nanoparticle. The form birefringence appears because of the anisotropic shape of shells ; the refractive index for the light polarized whose polarization is parallel to the elongation direction of ellipsoid is different from that for the light polarized perpendicularly. Moreover, the rotation of polarization plane is significantly enhanced at around the wavelength of localized surface plasmon resonance(LSPR). The difference in refractive index between two optical axes is as large as 0. 34 for a 600 nm light, which is more than twice of typical birefringence crystal calcite(0. 14 for visible light). It is speculated that the anisotropic shell induces the dependence of LSPR wavelength on the polarization direction of the incident light, which causes the polarization dependence of refractive index through the Kramers-Kronig relation. Less