In this paper, we study the thermal dissipation of Raman fiber laser and amplifier utilizing pure passive fiber as gain medium for the first time. Take into account the convective and conductive heat transferring process in the fiber, we consider the heat transferring and Raman conversion model based on the thermal conduction equations and the Raman coupled equations in the fiber. With the simulation of power distribution, the thermal profiles of Raman fiber laser are analyzed, including the transverse and longitudinal distributions of the heat load density, temperature, and thermal-induced refractive index change in the fiber. Meanwhile, the heat dissipation in multimode graded-index fiber and step-index fiber are also calculated and compared. The results show that the amplifier is superior to the resonator in heat alleviation, and the forward pumping scheme is also better to ease the thermal load than the backward and bidirectional pumping schemes, which have consult meaning for the suppression of thermal effects and the power scaling in Raman fiber lasers.

中文翻译：

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使用纯无源光纤的拉曼光纤激光器和放大器中热分布的理论分析

在本文中，我们首次研究了采用纯无源光纤作为增益介质的拉曼光纤激光器和放大器的热耗散。考虑到纤维中的对流和传导传热过程，我们考虑了基于纤维中热传导方程和拉曼耦合方程的传热和拉曼转换模型。通过功率分布仿真，分析了拉曼光纤激光器的热分布，包括热负荷密度、温度和光纤中热致折射率变化的横向和纵向分布。同时，还计算并比较了多模渐变折射率光纤和阶跃折射率光纤的散热情况。结果表明放大器在散热方面优于谐振器，