Impact Of Surface Plasmon Polariton In Lithium Niobate And Lanthanum Modified Lead Zirconate Titanate On Up-Conversion Emission

The development of the information age depends greatly on data storage and transmission,and therefore photonic devices with broad bandwidth and low loss have taken the lead.Since the miniaturization and integration of photonic devices are restricted by the diffraction limit,surface plasmon polariton（SPP）which propagates along the interface of a conductor and a dielectric brings a solution to this dilemma.Since the electromagnetic（EM）energy of SPP is confined within a sub-nanometer scale,confinement of the diffraction limit can be broken.In recent years,devices based on SPP have increasingly extensive applications in aspect of data storage,sensors,solar cell,among many others.To reduce the propagation loss of SPP,two-dimensional electron gas（2DEG）accumulated at the interfaces of polar materials and semiconductors due to polar catastrophe instead of metal structures provides new conditions for excitation of SPP.When the propagation loss of SPP is further compensated by optical gain from gain medium,it can be greatly lowered.Traditional research on SPP enhanced random lasing action relies on elaborate metal nanostructures,which require complicated processes,high fabrication cost,and are hard to integrated into electronic circuits.Transparent lanthanum modified lead zirconate titanate（PLZT）ceramics are known for their excellent dielectric,ferroelectric and piezoelectric properties,easy to be processed into thin film,and the process combining with a semiconductor is simple,with low cost and high rate of success,which is of great importance to miniaturization and integration into the photoelectronic devices.This thesis analyzes the accumulation of 2DEG and phase grating mediated excitation of SPP at the interface of degenerate semiconductor indium tin oxide（ITO）and Er³⁺doped lithium niobate（LN）in depth,and studies the energy coupling between long-ranged SPP and up-conversion emission（UCE）of rare earth ions.Furthermore,similar systems are extended to Zn Se coated transparent Nd³⁺doped PLZT（Nd:PLZT）ceramics,realizing SPP induced threshold reduction and intensity enhancement of random lasing action.Firstly,ITO film was deposited on the surface of polar single crystal Y-cut and Z-cut LN by magnetron sputtering,and therefore surface metallization and excitation of SPP are realized by electrostatic modification of polar LN to ITO film at the nanoscale.Utilizing Thomas-Fermi semiclassical charge screening model,the charge accumulation density in ITO film is calculated.It is found that the electron density within a sub-nanometer thick ITO film layer near the interface can be as high as that of noble metal Ag.Based on this,the permittivity of ITO film is calculated with Drude model.The real part of the permittivity near the interface turns from positive to negative.The formation of phase grating in LN is analyzed with photorefractive effect and hence the excitation of SPP at the ITO/LN interface is realized by combining with the phase matching condition.The excitation and propagation of SPP at the ITO/LN interface can be simulated with Otto attenuated total reflection（ATR）model.It is found that the propagation length of SPP can be up to an order of centimeter,1～2 orders of magnitude higher than conventional metal gratings,belonging to long-ranged SPP.Then,with rare earth ions Er³⁺doped into LN（Er,Fe:LN）,the excitation of SPP is verified with two laser beams incident from the same side.By recording gratings in the specimen without any overlapping,the excitation,propagation,and interference of long-ranged SPP can be verified.By measuring the scattering intensity distribution at the ITO/LN interface,the scattering of SPP exhibits unidirectional,which is explained by the multipolar analysis and backward wave scattering.The energy coupling efficiency between SPP and up-conversion emission can reach as high as 99.0%by measuring the dynamics curves of up-conversion emission in contrast experiments.Comparing the up-conversion emission intensity before and after the deposition of ITO film on Er,Fe:LN powder,it is found that the up-conversion emission intensity can be 3.5 times enhanced with SPP.With pumping light of different center wavelengths,the up-conversion emission intensity can be continually enhanced.In bulk Er,Fe:LN,laser oscillation with threshold feature based on SPP is observed.Finally,the polarity catastrophe resulted 2DEG accumulation is extended into Zn Se coated transparent Nd:PLZT ceramics where SPP enhanced random lasing action can be realized.The intensity of 2DEG accumulation at the Zn Se/Nd:PLZT interface is calculated with Poisson equation and Thomas-Fermi semiclassical charge screening model.It is again found that the charge intensity in a sub-nanometer layer of Zn Se near the interface can be as high as that of noble metal Ag.The spectra of random lasing action and shortened fluorescence lifetime above the threshold of pumping power are measured with a nanosecond pulse laser.By comparing the emission properties of bare Nd:PLZT powders and Zn Se coated Nd:PLZT powders,38 percent and 60 percent thresholds reduction and 7.6 times intensity enhancement of random lasing action and weak localization of light are obtained.Based on optical storage property of Nd:PLZT transparent ceramics,their applications in optical amplification are explored and a combined laser cavity is designed to realize the transformation between random lasing action and conventional lasing action.