All current gravitational wave (GW) observatories operate with Nd:YAG lasers with a wavelength of 1064 nm. The sensitivity of future GW observatories could benefit significantly from changing the laser wavelength to approximately 2 µm combined with exchanging the current room temperature test mass mirrors with cryogenically cooled crystalline silicon test masses with mirror coatings from amorphous silicon and amorphous silicon nitride layers. Laser light of the order of ten watts with a low relative power noise (RPN) would be required. Here we use a laboratory-built degenerate optical parametric oscillator to convert the light from a high-power Nd:YAG laser to 2128 nm. With an input power of 30 W, we achieve an output power of 20 W, which corresponds to an external conversion efficiency of approximately 67%. We find that the RPN spectrum marginally increases during the wavelength conversion process. Our result is an important step in the development of low-noise light around 2 µm based on existing low-noise Nd:YAG lasers.

中文翻译：

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将 1064 nm 的 30 W 激光转换为 2128 nm 的 20 W 激光以及相对功率噪声的比较


目前所有的引力波 （GW） 天文台都使用波长为 1064 nm 的 Nd：YAG 激光器。将激光波长更改为约 2 μm，并将当前的室温测试质量镜更换为低温冷却的晶体硅测试质量，以及来自非晶硅和非晶硅氮化物层的镜面涂层，可以显着提高未来 GW 天文台的灵敏度。需要 10 瓦左右且相对功率噪声 （RPN） 较低的激光。在这里，我们使用实验室制造的简并光学参量振荡器将来自高功率 Nd：YAG 激光器的光转换为 2128 nm。在 30 W 的输入功率下，我们实现了 20 W 的输出功率，相当于大约 67% 的外部转换效率。我们发现 RPN 光谱在波长转换过程中略有增加。我们的结果是在现有低噪声 Nd：YAG 激光器的基础上开发 2 μm 左右的低噪声光的重要一步。