Ménard Jean-Michel, Trabold Barbara M, Abdolvand Amir, Russell Philip St J
Opt Express. 2015 Jan 26;23(2):895-901. doi: 10.1364/OE.23.000895.
We use Raman amplification in hydrogen-filled hollow-core kagomé photonic crystal fiber to generate high energy pulses in pure single higher-order modes. The desired higher-order mode at the Stokes frequency is precisely seeded by injecting a pulse of light from the side, using a prism to select the required modal propagation constant. An intense pump pulse in the fundamental mode transfers its energy to the Stokes seed pulse with measured gains exceeding 60 dB and output pulse energies as high as 8 µJ. A pressure gradient is used to suppress stimulated Raman scattering into the fundamental mode at the Stokes frequency. The growth of the Stokes pulse energy is experimentally and theoretically investigated for six different higher-order modes. The technique has significant advantages over the use of spatial light modulators to synthesize higher-order mode patterns, since it is very difficult to perfectly match the actual eigenmode of the fiber core, especially for higher-order modes with complex multi-lobed transverse field profiles.
我们在充满氢气的空心蜂窝状光子晶体光纤中使用拉曼放大，以在纯单一高阶模式下产生高能量脉冲。通过从侧面注入光脉冲，并使用棱镜选择所需的模式传播常数，精确地为斯托克斯频率处所需的高阶模式提供种子。基模中的强泵浦脉冲将其能量转移到斯托克斯种子脉冲，测得的增益超过60 dB，输出脉冲能量高达8 μJ。利用压力梯度抑制在斯托克斯频率处向基模的受激拉曼散射。针对六种不同的高阶模式，对斯托克斯脉冲能量的增长进行了实验和理论研究。与使用空间光调制器来合成高阶模式图案相比，该技术具有显著优势，因为很难完美匹配光纤芯的实际本征模式，特别是对于具有复杂多瓣横向场分布的高阶模式。
