High Efficiency Raman Lasers Based on Zr-Doped Silica Hybrid Microcavities
High Efficiency Raman Lasers Based on Zr-Doped Silica Hybrid Microcavities
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DOI：
10.1021/acsphotonics.6b00608
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发表时间：
2016-12-01
期刊：
影响因子：
7
通讯作者：
Armani, Andrea M.
中科院分区：
文献类型：
--
作者：
Choi, Hyungwoo;Armani, Andrea M.
拉曼激光器形成了一种特别独特且通用的光学泵浦激光器。因为它们依赖于受激拉曼散射（SRS），受激拉曼散射由增益材料的振动频率而不是电子跃迁控制，所以发射波长由泵浦波长确定，从而实现宽的可调谐性。超高品质因数（Q）石英光学谐振器是拉曼激光器的理想平台，因为长的光子寿命导致大的循环光强度。先前的工作已经证明使用这些设备的阈值极低。然而，在二氧化硅器件中仅实现了中等的拉曼激光效率。在目前的工作中，我们证明了锆（Zr）掺杂的二氧化硅溶胶-凝胶涂层可以改善二氧化硅微腔拉曼激光器的性能。合成了不同浓度的锆掺杂溶胶-凝胶。本征拉曼增益的Zr掺杂的二氧化硅使用拉曼光谱测量，和值显示出一个明确的依赖于Zr掺杂剂的浓度。随后，超高Q值的二氧化硅环形微腔涂有不同的Zr掺杂的溶胶凝胶。使用765 nm光泵来表征拉曼激光性能，并且从790 nm开始检测涂覆器件的一阶和级联拉曼发射。使用光谱分析仪和光谱仪对拉曼激光发射和特征阈值曲线进行了定量。单向泵浦-拉曼转换效率随着Zr掺杂浓度的增加从3.37%显著提高到47.43%。
Raman lasers form a particularly unique and I versatile class of optically pumped laser. Because they rely on stimulated Raman scattering (SRS), which is governed by the vibrational frequency of the gain material and not electronic transitions, the emission wavelength is determined by the pump wavelength, enabling broad tunability. Ultrahigh quality factor (Q) silica optical resonators are an ideal platform for Raman lasers because the long photon lifetime results in large circulating optical intensities. Previous work has demonstrated extremely low thresholds using these devices. However, only moderate Raman lasing efficiencies have been achieved in silica devices. In the present work, we demonstrate that a zirconium (Zr)-doped silica sol-gel coating can improve the performance of a silica microcavity Raman laser. Several concentrations of Zr-doped sol-gel are synthesized. The intrinsic Raman gain of the Zr-doped silica is measured using Raman spectroscopy, and the values show a clear dependence on Zr dopant concentration. Subsequently, ultrahigh-Q silica toroidal microcavities are coated with the different Zrdoped sol gels. The Raman lasing performance is characterized using a 765 nm optical pump, and the first order and cascaded Raman emissions for the coated devices are detected starting at 790 nm. The Raman lasing emission and characteristic threshold curves are quantified using both an optical spectrum analyzer and an optical spectrograph. The unidirectional pump-to-Raman conversion efficiency exhibits a marked enhancement from 3.37 to 47.43% as the Zr concentration increases.