Minet Yannick, Herr Simon J, Breunig Ingo, Zappe Hans, Buse Karsten
Opt Express. 2022 Aug 1;30(16):28335-28344. doi: 10.1364/OE.463044.
Tunable light sources are a key enabling technology for many applications such as ranging, spectroscopy, optical coherence tomography, digital imaging and interferometry. For miniaturized laser devices, whispering gallery resonator lasers are a well-suited platform, offering low thresholds and small linewidths, however, many realizations suffer from the lack of reliable tuning. Rare-earth ion-doped lithium niobate offers a way to solve this issue. Here we present a single-frequency laser based on a neodymium-doped lithium niobate whispering gallery mode resonator that is tuned via the linear electro-optic effect. Using a special geometry, we suppress higher-order transverse modes and hence ensure single-mode operation. With an applied voltage of just 68 V, we achieve a tuning range of 3.5 GHz. The lasing frequency can also be modulated with a triangular control signal. The freely running system provides a frequency and power stability of better than =20MHz and 6 %, respectively, for a 30-minute period. This concept is suitable for full integration with existing photonic platforms based on lithium niobate.
可调谐光源是许多应用的关键 enabling 技术，如测距、光谱学、光学相干断层扫描、数字成像和干涉测量。对于小型化激光器件，回音壁模式谐振器激光器是一个非常合适的平台，具有低阈值和小线宽，然而，许多实现方式都存在缺乏可靠调谐的问题。稀土离子掺杂铌酸锂提供了一种解决这个问题的方法。在这里，我们展示了一种基于掺钕铌酸锂回音壁模式谐振器的单频激光器，它通过线性电光效应进行调谐。使用特殊的几何结构，我们抑制了高阶横向模式，从而确保了单模运行。仅施加 68 V 的电压，我们就实现了 3.5 GHz 的调谐范围。激光频率也可以用三角控制信号进行调制。自由运行系统在 30 分钟内分别提供优于 =20MHz 和 6% 的频率和功率稳定性。这个概念适用于与现有的基于铌酸锂的光子平台进行完全集成。
