| The energy band theory, which makes us understand the differences between metals, semiconductors, and insulators clearly. For a long time, metallic materials are only usded as conductors. With the study of the metal surface plasmon polaritons (SPPs), it is found that due to the interacting of free electrons in the metal with the electromagnetic wave (light), new optical phenomena emerge,which in turn extends the metallic applications.Surface plasmon polaritons (SPPs) travel along the metal-dielectric interface. The term "Surface Plasmon Polariton" explains that the wave involves both charge motion in the metal ("surface plasmon") and electromagnetic waves in the dielectric ("polariton"). In recent years, advances in micro-and nano-fabrication technologies (FIB, EBL, etc.) continue to improve. All of these technologies provide us favorable conditions when we are studying the interaction between nano-scale metal and light. Current research directions include:enhanced optical transmission, enhanced fluorescence, super-resolution imaging, invisibility cloak, negative refraction material, electromagnetic induced transparency, solar cells, plasmon lasers and so on.The paper began with the theoretical and experimental studies on SPP with possible applications in optics. By design perforated metal microstructure, we realized the light polarization rotation. Electromagnetic waves can be confined in a specific area of micro-and nano-structures that can achieve a strong field strength in a very small size, this make it possible to achieve fluorescence enhancement. The main contents are as follows:1、Different from the traditional planar chiral materials for optical rotation with the low efficiency, multi-layer, non-zero order transmission drawbacks, we realized an enhanced optical rotation of the zero-order transmitted light through a single silver film with an array of perforated S-shaped holes. Because of the existence of SPP and LSP resonances, we achieved a great optical rotation in experiment. (Rotation rate of the experiment was 4.1 × 105degrees/mm, far greater than any kind of natural materials, such as quartz crystal with its rotation rate of 17degrees/mm).Through precise design of micro-structures, SPPs and LSPs resonances can be excited simultaneously. LSPs resonance can result in the radiation output whose polarization perpendicular to the polarization of the incident wave. While for SPP, its phase would be delayed when going through the structure of the sample. Thus the thickness of the sample can modulate the phase and amplifier of the excited electromagnetic caused by SPPs and LSPs resonances. Because of the superposition effect we achieved an effective control of the zero-order transmitted optical polarization rotation. With the increases of the thickness of the silver film, the optical rotation angle increases nonlinearly which is different from the conventional chiral materials. Especially when the silver film thickness is 245nm,90° optical rotation is realized in the zero-order transmission. This study provide a way for future design of micro- and nano-sized polarization devices.2、Since the SPPs and the LSPs can be very strongly confined in the micro- and nano-scale, we can extend this effect to the research of fluorescence enhancement for Er:Yb:YCOB crystal (YCOB crystals doped with erbium and ytterbium materials, its absorption peak is 980nm,and emission peak is 1550nm). We have designed different periodic array structures to study the fluorescence enhancement. It was found that when the resonance wavelength of the metallic periodic structure is at the YCOB emission peak, the fluorescence enhancement is 15 times larger than other structures. While for the structures whose resonance is at the absorption peak, no significant fluorescence enhancement is obtained. |
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