光子灯笼中模式耦合及其对光束质量的影响

Mode Coupling in Photonic Lantern and Its Influence on Beam Quality

摘要: 通过仿真光子灯笼中存在模式的相干叠加过程，利用模式耦合理论和M2因子的二阶矩算法，得到了输出光斑形态、耦合效率和光束质量随模式间相位差、功率占比以及偏振的变化规律，分析了对光子灯笼进行控制时需要考虑的因素。研究表明，只有同时控制光子灯笼输入端各模式的功率占比和相位差，才能得到耦合效率较高的高光束质量的输出；通过对输入端振幅、相位和偏振的合理控制可以得到需要的特殊的光斑形态。

Abstract: Through simulating the coherence superposition process of the existential mode in the photonic lantern, the beam spot shape, combining efficiency and the changing rule of the beam quality with the phase difference between modes, power ratio and polarization are obtained on the basis of the mode coupling theory and the second moment algorithm of M2 factor. In addition, the factors which need to be considered in controlling the photonic lantern are also analyzed. Research indicates that the output can be of high beam quality and high coupling efficiency only on condition that the input power ratio and phase difference of various mode of photonic lantern are under control at the same time; the needed special spots can be achieved through reasonable control of the input amplitude, phase and polarization.