Study On The Wide-band Plasmon And All-optical Logic Gates Of Liquid Metal Nanodroplets

Due to their excellent nonlinear optical effect,noble metal nanoparticles have been widely concerned in the fields of ultrafast optics,photocatalysis,phototherapy and all-optical modulation.The nonlinear effect of metal nanoparticles is caused by the localized surface plasmon resonances(LSPR)effect.Metal nanoparticles can localize the light field on the surface and form a very strong local field,which enhance the nonlinear effect of materials.Compared with nonle metals such as gold and silver,liquid metal has the advantages of low cost,easy preparation,non-toxic effects,and have been found to have local surface plasmon resonance effect.Liquid metal has been widely used in electricity,but seldom in the field of optics.In this paper,we mainly introduce the LSPR and nonlinear optical effects of liquid metal nanodroplets,and apply them on all-optical logic gate devices.The main research contents of this paper include:(1)Briefly introduce the development of surface plasmon theory and its application in various fields.This paper introduces the research status of liquid metal,especially the research progress of liquid metal in optics in recent years,and investigates the research status of all-optical logic gate,mainly introduces the research progress of all-optical logic gate using phase modulation effect.(2)In this paper,the mechanism of surface plasmon effect and its theoretical analysis are introduced from bulk and nano aspects.The extinction cross-section of metal nanoparticles is simulated by quasi-static approximation and discrete dipole approximation(DDA).We introduce several nonlinear optical phenomena caused by the third-order nonlinear effect of metal nanoparticles,mainly including the phase modulation caused by the real part of the third-order polarizability(?R(3))and the saturated absorption and anti-saturated absorption caused by the imaginary part of the third-order polarizability(?I(3)).(3)We introduce the preparation method of liquid metal nanodroplets.The composition and morphology of the materials were characterized by transmission electron microscope(TEM)?scanning electron microscope(SEM)and energy dispersive spectrum(EDS).According to the dielectric function of the material,the resonance absorption effect of nanodroplets is simulated.According to the results of linear absorption spectrum,the LSPR effect of liquid metal nanodroplets was confirmed.(4)This paper introduces the nonlinear optical effect of liquid metal nanodroplets Firstly,the spatial self phase modulation(SSPM)is realized at 405nm,532nm,776nm,1064nm and 3.5?m.The nonlinear refractive index of the material is calculated according to the self-phase modulation effect.Secondly,the spatial cross-phase modulation(SXPM)is realized at visible-infrared waveband.Thirdly,the non-linear absorption coefficient of the material is measured by Z-scan method,which shows that the liquid metal nanodroplets have a wide band saturated absorption characteristic.(5)This paper introduces the realization method and experimental results of all-optical logic gate based on SSPM and SXPM,mainly introduces the design of experiment and the construction of experimental optical design.We demonstrate the results of all-optical logic gate in 532nm and 2 ?m.The transient absorption test based on the pump-probe technology shows that the material has ultrafast photothermal response and this material can be used in ultrafast all-optical modulator.