Raman scattering provides a convenient mechanism to generate or amplify light at wavelengths where gain is not otherwise available. When combined with recent advancements in high-power fiber lasers that operate at wavelengths ~2 μm, great opportunities exist for Raman systems that extend operation further into the mid-infrared regime for applications such as gas sensing, spectroscopy, and biomedical analyses. Here, a thulium-doped fiber laser is used to demonstrate Raman emission and amplification from a highly nonlinear silicon core fiber (SCF) platform at wavelengths beyond 2 μm. The SCF has been tapered to obtain a micrometer-sized core diameter (~1.6 μm) over a length of 6 cm, with losses as low as 0.2 dB cm⁻¹. A maximum on-off peak gain of 30.4 dB was obtained using 10 W of peak pump power at 1.99 μm, with simulations indicating that the gain could be increased to up to ~50 dB by extending the SCF length. Simulations also show that by exploiting the large Raman gain and extended mid-infrared transparency of the SCF, cascaded Raman processes could yield tunable systems with practical output powers across the 2–5 μm range.

拉曼散射提供了一种方便的机制来产生或放大无法获得增益的波长的光。当与工作波长约为 2 μm 的高功率光纤激光器的最新进展相结合时，拉曼系统存在巨大的机会，可以将操作进一步扩展到中红外区域，用于气体传感、光谱学和生物医学分析等应用。在这里，掺铥光纤激光器用于演示高度非线性硅芯光纤 (SCF) 平台在波长超过 2 μm 时的拉曼发射和放大。SCF 已逐渐变细，以获得长度为 6 cm 的微米级核心直径 (~1.6 μm)，损耗低至 0.2 dB cm ^-1。在 1.99 μm 处使用 10 W 峰值泵浦功率获得了 30.4 dB 的最大开关峰值增益，模拟表明通过延长 SCF 长度可以将增益增加至约 50 dB。模拟还表明，通过利用 SCF 的大拉曼增益和扩展的中红外透明度，级联拉曼过程可以产生在 2-5 μm 范围内具有实际输出功率的可调系统。