Surface Plasmon Polaritons In Metal Nanowires And Their Photothermal Applications

In the boom of contemporary optical information technology research,micro/nanophotonic devices and processing technology,attracting many scholars’attention,have been through a thriving development.The chemically synthesized metal nanowires(NWs)have been chosen as excellent carriers of surface plasmon polaritons(SPPs)because of their advantages of few internal scattering points,good surface smoothness and low transmission loss.Thus they are widely applied in the micro/nanophotonic devices such as nano-waveguides,nano-couplers,nano-sensors,and transparent electrodes.The metal NW SPP mode analysis laies a solid foundation for the design of these micro/nanophotonic devices as well as the exploration of their physics behind.As a key part of the micro/nanoprocessing technology,the nano-connection is a bridge between nano-devices and macroscopic systems,and has gradually penetrated into the whole life cycle of various photon micro/nanodevices.Among current typical nano-connection technology,the light-controlled nano-connection has become the focus of many scholors,because of its advantages of flexible operation,high controllability and high energy efficiency.Based on the research background above,this paper mainly studies SPPs in metal NWs and their photothermal applications.From theory to experiment,we launch a series of studies on the silver NWs(a representative of the metal NWs):reveal the physics of the metal NW SPP mode,study the control of the mode and develop light-controlled SPP nano-healing technology(a light-controlled nano-connection technique).For the analysis of the metal NW SPP mode derived from micro/nanophotonic devices,we identify and control multiple leaky SPP modes simultaneously excited in silver NWs by means of combining far-field real-space imaging and Fourier-space imaging.Firstly,the mode features of five typical SPP modes including both bound modes and leaky modes in silver NWs are provided.Secondly,the experimental results of NWs with single,double and triple excited leaky SPP modes are presented sequentially.We also investigate the effect of excitation wavelengths and NW diameters on the number and optical properties of excited leaky SPP modes.For the surface plasmonic photothermal effect derived from micro/nano processing technology,we explore and develop a low-cost and easy-operation technique of optically controllable and targeted nano-healing based on the plasmonic photothermal effects.Nanogaps,as a kind of typical nanodefects,are repaired by this technique.The process of nano-healing is divided into two stages:a constant-power stage and an increasing-power stage.In the first stage of nano-healing,constant-power(almost low power)laser shots make the nanogap width small.In the second stage of nano-healing,increasing-power laser shots cause the nanogap width further reduced.With the optimum power,the bottom of the nanogap is connected.The effects of laser power,number of laser shots,NW diameters,etc.on these two stages of nano-healing are specifically demonstrated both in simulation and experiments.Finally,we summarize the work of this paper,and overlook the future research of metal NW SPPs.