无源Ge_(28)Sb_(12)Se_(60)硫系玻璃微球谐振腔的制备及其光学回廊模式表征

Fabrication and Characterization of Passive Microsphere Resonators Based on Ge_(28)Sb_(12)Se_(60) Chalcogenide Glass

为了对硫系玻璃微球谐振腔在中短红外波段的光学回廊模式进行理论研究和实验表征,用熔融淬冷法制备了组分为Ge28Sb12Se60的无砷环保型硫系玻璃,并在此基础上采用漂浮粉末熔融法批量制备出直径分布为50~200μm的微球谐振腔.在显微镜下挑选出直径分别为112.01μm和57.63μm的一大一小两颗微球与自制石英微纳光纤锥进行近场耦合实验,以窄带宽可调谐激光器为泵浦源测试此耦合系统在1 530~1 560nm波段的光谱.光谱中明显观测到由微球回廊模式谐振引起的等间距分布的光谱吸收峰.小球、大球的吸收峰间距分别为5.22nm和2.60nm,与米氏散射理论计算得出的一阶TE回廊模谐振峰间距基本相符.实验结果表明新型Ge28Sb12Se60硫系玻璃有望在红外微球光子器件如窄带滤波器、微球喇曼激光器、高灵敏度传感器等领域获得重要应用.

The fabrication and characterization of microsphere resonators was researched based on an arsenic-free chalcogenide glass whose composition can be represented as：Ge28Sb12Se60.Bulk Ge28Sb12Se60 glasses was fabricated and then crushed into powders.Glass powders were fed into a self-developed furnace and were melted into liquid forms.Molten glass powders were transformed into microspheres due to surface tensions and were cooled/collected in the output of the furnace.Microsphere fabricated in our lab have diameters ranging from 50~200μm.Two microspheres with diameters of 112.01μm and57.63μm were selected for near field coupling experiments with silica fiber tapers.The microsphere/fiber taper coupling system with a narrow-bandwidth tunable laser was pumped and the spectra of the coupling system for the spectral range of 1 530~1 560 nm was measured.Periodically spaced absorption peaks were clearly noted in the measured spectra,which were attributed to optical resonances happened in corresponding wavelengths due to whispering gallery modes.The spacings of adjacent absorption peaksare 5.22 nm and 2.60 nm for the 112.01μm and 57.63μm spheres,which are in good accordance with spacings of first-order WGMs calculated with the classic Mie scattering theory.According to the experimental results,Ge28Sb12Se60 glass can be used as a promising alternative to conventional Arsenicbased chalcogenide glasses for fabricating infrared microsphere resonators, which have important applications in the fields of narrow-bandwidth filters,Raman lasers,and high sensitivity optical sensors.