Rare-earth-doped on-chip microlasers are of great significance in both fundamental research and engineering. To the best of our knowledge, this is the first report of Yb³⁺-doped and Er³⁺/Yb³⁺-codoped on-chip microsphere lasers fabricated via sol-gel synthesis. Laser emissions were observed in a band around 1040 nm in both Yb³⁺-doped and Er³⁺/Yb³⁺-codoped resonators pumped at 980 nm and had measured ultralow thresholds of 5.2 µW and 0.6 µW, respectively. Both single-mode and multi-mode emissions were recorded around 1040 nm in these lasers. Single-mode and two-mode emissions were obtained at 1550 nm in the Er³⁺/Yb³⁺-codoped lasers when pumped at 980 nm and 1460 nm, respectively. Furthermore, quality factors induced by different loss mechanisms in the microsphere lasers are theoretically estimated. These resonators are expected to contribute to the high-density integration of on-chip silica-based microlasers.

中文翻译：

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Yb3+ 掺杂和 Er3+/Yb3+ 共掺杂片上微球激光器的演示

稀土掺杂的片上微型激光器在基础研究和工程方面都具有重要意义。据我们所知，这是通过溶胶-凝胶合成制造的 Yb ³⁺掺杂和 Er ³⁺ /Yb ³⁺共掺杂片上微球激光器的第一份报告。在 980 nm 泵浦的Yb ³⁺掺杂和 Er ³⁺ /Yb ³⁺共掺杂谐振器中，在大约 1040 nm 的波段内观察到激光发射，并分别测得了 5.2 µW 和 0.6 µW 的超低阈值。在这些激光器中，在 1040 nm 附近记录了单模和多模发射。在 Er ³⁺ /Yb ^{3+ 中}在 1550 nm 处获得单模和双模发射-分别在 980 nm 和 1460 nm 泵浦时的共掺杂激光器。此外，理论上估计了由微球激光器中不同损耗机制引起的质量因素。这些谐振器有望促进片上硅基微型激光器的高密度集成。