带有多孔二氧化硅间隔层的导模共振光栅实现染料激光器发射增强  

Enhanced dye lasing emission by guided-mode resonance grating with mesoporous silica as spacing layer

作　　者：崔涛 王康妮 高凯歌 钱林勇 Cui Tao;Wang Kang-Ni;Gao Kai-Ge;Qian Lin-Yong(School of Physical Science and Technology,Yangzhou University,Yangzhou 225009,China;School of Physics and Electronic Engineering,Jiangsu Normal University,Xuzhou 221116,China)

机构地区：[1]扬州大学,物理科学与技术学院,扬州225009 [2]江苏师范大学,物理与电子工程学院,徐州221116

出　　处：《物理学报》2021年第1期286-294,共9页Acta Physica Sinica

基　　金：国家自然科学基金青年科学基金(批准号:61805210,11704162);江苏省高校自然科学研究基金(批准号:18KJB510048);江苏省自然科学基金青年基金(批准号:BK20170482)资助的课题.

摘　　要：导模共振光栅是一种典型的平面波导共振结构,可在光栅表面或波导层内形成较强的局域电场,能增强光与物质的相互作用.本文在导模共振结构的光栅层和基底层之间,引入低折射率的多孔二氧化硅间隔层,显著增强了局域电场与增益介质的接触度.结果表明,引入多孔二氧化硅后,共振产生的电场增强区域上移至激光染料层,增加了激光染料与电场的相互作用,实现了激光出射增强.本文基于时域有限差分法,对结构参数进行分析优化,研究了820 nm共振波长激发下的出射激光特性,得到了连续的激光出射,其能量阈值约为2.5 mJ/cm^2,线宽约为0.3 nm.本文提出的结构实现了对表面局域电场的有效调控,增强了激发光与增益介质的相互作用,不但可应用于激光器,还为其它发光器件的设计提供了参考.The enhancement of lasing emission intensity of dye laser is particularly important and urgently required due to a broad range of optical and electrical applications.The guided-mode resonance(GMR)effect occurs in a periodic waveguide structure where an incident wave is coupled to a leaky waveguide mode,and yields a resonance peak.The resonance wavelength can be easily controlled by adjusting the period of the grating,thickness of the waveguide layer,and refractive index of the covering materials.By using band edge states,one may be able to excite optical resonances extended over the entire structure surface,thereby achieving field enhancement over a large area.In this study,mesoporous silica with low refractive index is introduced between the grating layer and the substrate layer of the GMR structure to significantly enhance the contact between local electric field and gain medium.For comparison,another structure using SU-8 with high refractive index as the spacing layer is also proposed.It is clearly observed that the maximum of the electric field intensity is highly localized inside the SU-8 waveguide grating layer.However,it is shifted upward to the gain medium layer in the mesoporous silica structure due to the reverse symmetry waveguide structure design.Therefore,the interaction between laser dye and electric field is increased to further enhance the lasing emission.Besides the refractive index,the waveguide layer,other structural parameters such as thickness of each layer and grating period also affect the electric field distribution in the GMR structure.Based on the finitedifference time-domain method,the structural parameters are analyzed and optimized.According to the simulation results,the structure parameters TWG=3.5μm,L=700 nm,and TTiO2= 20 nm are chosen as the guideline for designing the dye laser,which generates the resonance wavelength of 820 nm the same as the absorption wavelength of dye molecules.Additionally,the laser characteristics excited by pump light with the wavelength of 820 nm are stud

关 键 词：光栅 导模共振 染料激光器 多孔二氧化硅 

分 类 号：TN248.3[电子电信—物理电子学]