Low-threshold High-quality Surface Plasmon Lasers Based On Perovskite Nanosheets

Perovskite surface plasmon lasers can break the diffraction limit by taking advantage of the excellent optical properties of perovskite materials and the surface plasmon effect to achieve room temperature laser emission,which has a wide range of applications in optical interconnection,biological detection,medical treatment,nano lithography,data storage and other fields.Quality factor(Q)is an important parameter of characterization of optical resonator loss,small quality factor means that large optical loss,the laser has high laser threshold,the device is in use process will produce a large number of joule heat,cause life is short,exist the problem of large energy consumption at the same time,is not conducive to the integrated application of laser.Therefore,the study of high quality factor perovskite surface plasmid laser needs further research.The gain medium morphology and the surface roughness of the metal film have important effects on the threshold value and quality factor of the perovskite surface plasmon laser.The surface topography of metal substrates requires a lower surface roughness to reduce the loss.The gain medium is mostly nanowire structure,and its small contact area makes it have large edge and interface loss,which has the problem of low quality factor.In the paper,surface plasmon laser with Semiconductor-Insulator-Metal(SIM)structure is produced based on Methylamine lead iodine perovskite nanoplate which acts as gain medium,the insulator is silicon dioxide and the metal is silver.It is expected to achieve low threshold surface plasmon laser emission with high quality factor,by combining high quality Whispering Gallery Mode resonator with surface plasmon,which can improve optical feedback and reduce scattering loss.This study will provide a technical basis for the preparation of surface plasmon structures.The research content of this paper mainly includes the following aspects:1.Flat metal-insulator film was prepared.In SIM structure,the surface roughness of metal-insulator film has an important effect on the combination between it and the gain material,which affects the energy transfer process between excitons and surface plasmons and the surface scattering loss and,in turn,affects the laser threshold,in order to achieve low threshold from excimer laser,such as surface preparation must be flat metal-medium thin film.By adding alumina layer and improving the deposition rate of magnetron sputtering,a relatively smooth silver film with a roughness of about 1nm was prepared,and on this basis,a silicon dioxide film with a surface roughness of less than 1.5 nm was prepared.2.The perovskite nanoplatelets were transferred nondestructive by thermal release method.The methylamine lead iodine perovskite nanoplatelets used in this paper are prepared on mica substrate by two-step vapor deposition method.Because the mica substrate has strong absorption of pump light,it is not conducive to the preparation and characterization of SIM structure,so it is necessary to transfer the perovskite nanoplatelets.The thermal release tape transfer method was used to transfer methylamine lead iodine perovskite nanoplatelets,and the transfer process was studied.The methylamine lead iodine perovskite nanoplatelets with uniform geometry were transferred to different substrates,and the MAPb I₃ before and after the transfer was characterized by XRD and AFM,proving that the transfer process was nondestructive.2.The surface plasmon laser of perovskite nanoplatelets was prepared and characterized.When perovskite nanoplatelet gain medium is introduced into the SIM structure,the scattering loss at the edge and interface is significantly reduced,the larger contact area to ensure the photonic-surface plasmon modal overlap and can effectively promote the energy transfer between the exciton and the surface plasmon,and provide enough optical gain to compensate the loss,so that the laser threshold can be reduced.The prepared MAPb I₃ nanoplatelet was transferred to the prepared Si O₂-Ag thin film by heat release method to prepare SIM structure surface plasmon laser,and the preliminary characterization was carried out.The SIM structure surface plasmon laser is excited at room temperature by a femtosecond pulse laser with a wavelength of 343 nm through a self-built reflected light path.The lasing threshold is41.53?J/cm²and lower than the reported laser with the same structure.The full width of the maser peak is 0.44 nm at 778.65 nm at the energy density of 44.36?J/cm²,and the Q value above 1700.In conclusion,the thermal release method was used to realize the nondestructive transfer of perovskite nanoplatelets,and the surface plasmon laser based on the gain medium of perovskite nanoplatelets was used to realize the room temperature lasing with low threshold and high quality factor.