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中国物理学会期刊

2 μm波段硫系玻璃微球激光器的制备和表征

CSTR: 32037.14.aps.68.20181817

Fabrication and characterization of chalcogenide glass microsphere lasers operating at 2 μm

CSTR: 32037.14.aps.68.20181817
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  • 工作在2\;\textμ\rmm波段附近的中红外微球激光器在生物医学传感、激光雷达、窄带光学滤波和空气污染监控等领域具有重要的应用价值. 本文以自制的Tm3+-Ho3+共掺的Ge-Ga-Sb-S (2S2G)硫系玻璃为基质材料, 采用玻璃粉末高温漂浮熔融法批量制备了高品质(典型品质因数大于105)硫系玻璃微球. 优选一颗直径为205.82\;\textμ\rmm的微球为实验对象, 利用光纤锥耦合法对其进行光学近场耦合实验. 在808 nm抽运光的作用下, 在1.8—2.1\;\textμ\rmm波段处可观测到明显的荧光回廊模现象. 当抽运功率达到0.848 mW的阈值时, 可在2080 nm附近观测到明显的激光输出. 上述实验结果表明本文采用的2S2G硫系玻璃具有用于制备工作在中远红外波段的有源光学/光电子学器件的潜力.

     

    Microsphere lasers operating at the 2\;\textμ\rmm band have important applications in the fields of bio-medical sensing, laser radars, narrow linewidth optical filtering, and air-pollution monitoring. In this work, we utilize a novel type of chalcogenide glass, whose composition is Ge-Ga-Sb-S or 2S2G, to fabricate microsphere lasers. Compared with chalcogenide glasses used in previous microsphere lasers, this 2S2G glass is environmentally friendly. It also has a lower melting temperature and a higher characterization temperature, implying that 2S2G microspheres can be fabricated at lower temperatures and the crystallization problem happening in the sphere-forming process can be mitigated. A \textTm^3+\text-\textHo^3+ co-doping scheme is applied to the 2S2G glass, so that fluorescence light at ~2\;\textμ\rmm can be obtained from the bulk glass. Owing to the superior properties of the 2S2G glass, we can utilize a droplet method to mass-produce hundreds of high-quality 2S2S microspheres in one experimental run. The diameters of microspheres fabricated in this work fall in a range of 50−250\;\textμ\rmm and typical quality factors (Q factor) of microspheres are higher than 105. As a representative example, we characterize the optical properties of a 205.82\;\textμ\rmm diameter 2S2G microsphere. This microsphere is placed in contact with a silica fiber taper, so that the pump light can be evanescently introduced into the microsphere and the fluorescence light can be evanescently collected from the microsphere. A commercial laser diode (808 nm) is used as a pump source and an optical spectral analyzer is used to measure the transmission spectra of the microsphere/fiber taper coupling system. Apparent whispering gallery mode patterns in the ~2\;\textμ\rmm band can be noted in the transmission spectra of the coupling system. When the pump power increases beyond a threshold of 0.848 mW, a lasing peak at 2080.54 nm can be obtained from the coupling system. Experimental results presented in this work show that this 2S2G chalcogenide glass is a promising base material for fabricating various active optical/photonic devices in the middle-wavelength and long-wavelength infrared spectra.

     

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