Pongchalee P, McNeil B W J
Opt Express. 2023 Jul 31;31(16):26673-26684. doi: 10.1364/OE.494481.
Previous simulation studies of cavity based free electron lasers (FELs) have utilised models which average the optical field in the FEL interaction over an integer number of radiation wavelengths. In this paper, two unaveraged simulation codes, OPC and Puffin, are combined to enable modelling, for the first time, of a cavity based FEL at the sub-wavelength scale. This enables modelling of effects such as coherent spontaneous emission from the electron beam and sub-wavelength cavity length detuning. A cavity FEL operating in the mid-infrared is modelled and it is shown that, for small sub-wavelength cavity detunings, the FEL can preferentially lase at the third harmonic of the fundamental FEL wavelength. This novel result suggests other modes of operation may be possible and opens up cavity-based FEL operation to investigation of further, potentially useful, modes of operation.
先前对基于腔的自由电子激光器（FEL）的模拟研究使用的模型是在整数个辐射波长上对FEL相互作用中的光场进行平均。在本文中，将两个非平均模拟代码OPC和Puffin相结合，首次实现了在亚波长尺度上对基于腔的FEL进行建模。这使得能够对诸如电子束的相干自发辐射和亚波长腔长失谐等效应进行建模。对一个工作在中红外波段的基于腔的FEL进行了建模，结果表明，对于小的亚波长腔失谐，FEL可以优先在基频FEL波长的三次谐波处产生激光。这一新颖的结果表明可能存在其他运行模式，并为基于腔的FEL运行开启了对更多潜在有用运行模式的研究。
