摘要
提出一种利用辅助光调控高功率掺镱光纤放大器中增益分布,以控制信号光的受激拉曼散射(SRS)增益、提高SRS阈值的方法.基于数值模拟分析了辅助光的波长以及辅助光和信号光的功率比例对放大器SRS阈值的影响规律.计算结果显示,通过引入适当波长和功率的辅助光可以有效提升放大器的SRS阈值.
Abstract
A novel technique to suppress the stimulated Raman scattering(SRS)effect in high-power ytterbium-doped fiber amplifier is proposed and theoretically investigated by introducing an auxiliary laser to manipulate the gain distribution in the amplifier.By injecting an auxiliary laser with shorter wavelength than the signal into the amplifier,the auxiliary laser,owing to its larger stimulated emission cross-section,initially extracts a significant portion of the laser gain.At this point,the gain of the longer-wavelength signal laser is suppressed to a certain extent.As the pump power is depleted in the rear segment of the gain fiber,the amplified auxiliary laser,which has larger absorption cross-section than the signal,is gradually absorbed by the active fiber and transfers its power to the signal laser.This process enhances the gain of the long-wavelength signal laser,enabling it to be rapidly amplified at the end of the amplifier.Compared with the amplification of the singular signal laser,the introduction of an extra auxiliary laser shifts the high-gain region of the signal laser to the rear portion of the amplifier,thereby reducing the effective length and alleviating the interaction strength between the signal laser and Stokes wave,in order to obtain a higher SRS threshold.The SRS threshold of a 20 μm/400 μm fiber amplifier is investigated by using numerical simulation under different wavelengths of the auxiliary laser and different power ratios of the signal laser to auxiliary laser.The results indicate that incorporating an auxiliary laser with an appropriate wavelength and power level can significantly reduce the interaction strength between the signal and Stokes wave,thereby enhancing the SRS threshold of the amplifier efficiently.Specifically,in a 1080 nm fiber amplifier utilizing a 20 μm/400 μm ytterbium-doped large mode area fiber,if the total power of the 1080 nm signal and 1040 nm auxiliary laser is set to 200 W,while with a power ratio of 1∶25,the SRS threshold increasing from 3.14 kW(singular signal laser)to 8.42 kW can be anticipated.Moreover,based on the auxiliary laser amplification technique that suppresses the SRS effect,the output power enhancement of fiber lasers with the structure of master oscillator power amplifier(MOPA)is also analyzed.This technical solution is relatively straightforward to implement and can be seamlessly integrated with other techniques aimed at reducing the SRS effect,which is promising to promote further power scaling of all-fiber amplifier.
基金项目
国家重点研发计划(2022YFB3606000)
国家自然科学基金(62105240)
国家自然科学基金(62275190)
国家自然科学基金(62075159)
山东省重点研发计划(2020CXGC010104)
山东省重点研发计划(2021CXGC010202)
天津大学自主创新基金(2023XPD-0020)
中国兵器工业集团有限公司激光器件技术重点实验室开放基金(QT23120019)
泰山产业领军人才项目(tscx202312163)
维普
万方数据