Yin Ke, Zhang Bin, Yang Weiqiang, Chen Hongwei, Hou Jing
College of Optoelectronic Science and Engineering, National University of Defense Technology, Changsha 410073, China.
Opt Express. 2013 Jul 1;21(13):15987-97. doi: 10.1364/OE.21.015987.
In this paper, we report on cascaded Raman scattering (RS) in a highly germanium-doped silica fiber (HGDF) pumped by a picosecond pulsed master oscillator power amplifier (MOPA) system at 1064 nm in the normal dispersion regime. Benefited by the higher Raman gain of germanium (GeO2) than silica in the core, the length of the HGDF is only several meters. The broadest output spectrum comprises of 10 orders Raman stokes waves and eventually evolves into a supercontinuum (SC) spanning from 1000 to beyond 2100 nm with an output average power up to Watt scale. To the best of our knowledge, this is the first time to obtain such a broad cascaded RS spectrum in a short length of GeO2-doped step index silica fiber. We also numerically investigate the propagation of picosecond pulses in this HGDF based on the generalized nonlinear Schrödinger equation (GNLSE) which includes most of the dispersive and nonlinear effects, and the simulation results are in fairly good agreement with our experiments. It is believed that the numerical approach adopted in this paper is very beneficial for designing customized cascaded Raman fiber lasers before experimental implementations.
在本文中，我们报道了在正常色散区域由1064nm皮秒脉冲主振荡功率放大器（MOPA）系统泵浦的高掺锗石英光纤（HGDF）中的级联拉曼散射（RS）。受益于纤芯中锗（GeO2）比石英更高的拉曼增益，HGDF的长度仅为几米。最宽的输出光谱由10阶拉曼斯托克斯波组成，最终演变成一个跨越1000至2100nm以上的超连续谱（SC），输出平均功率达到瓦级。据我们所知，这是首次在短长度的掺GeO2阶跃折射率石英光纤中获得如此宽的级联RS光谱。我们还基于包含大多数色散和非线性效应的广义非线性薛定谔方程（GNLSE）对皮秒脉冲在该HGDF中的传播进行了数值研究，模拟结果与我们的实验相当吻合。相信本文采用的数值方法对于在实验实施之前设计定制的级联拉曼光纤激光器非常有益。
