Dynamic Compensation of Refractive-Index-Mismatch-Induced Aberrations in Laser Processing

激光直写技术为三维空间的高精度光子芯片制造提供了一种灵活的加工方案。但是在材料内部加工的过程中，由材料折射率过高与环境介质间折射率失配引起的深度依赖球面像差，会导致聚焦光斑轴向拉伸(长度达数微米)，严重影响制造的加工精度。利用自适应光学的方法，通过将空间光调制器添加到具有折射率失配像差的共轭光路中，可以实现动态补偿波前相位。本文从理论分析入手，基于波前像差理论，利用泽尼克多项式实现对球面像差的矫正，对比说明了补偿前后两种情况下点扩散函数的强度分布，并进一步探讨了不同数值孔径(NA)条件下的补偿效果。结果表明，在高NA系统中，补偿相位的引入能够显著提高焦点处的能量集中度，并使点扩散函数的全宽半高(FWHM)显著收缩，峰值强度衰减得到改善。Laser direct writing technology provides a flexible fabrication solution for high-precision photonic chip manufacturing in three-dimensional space. However, during material internal processing, depth-dependent spherical aberration induced by refractive index mismatch between high-refractive-index materials and ambient media causes axial elongation of the focused spot (extending to several micrometers), severely compromising fabrication precision. By integrating a spatial light modulator into the conjugate optical path with refractive index mismatch-induced aberration, adaptive optics enables dynamic wavefront phase compensation. Starting from theoretical analysis, this work employs wavefront aberration theory to correct spherical aberration using Zernike polynomials. A comparative study of the point spread function (PSF) intensity distribution before and after compensation demonstrates that the introduction of phase compensation significantly enhances energy concentration at the focal point in high numerical aperture (NA) systems, accompanied by substantial contraction of the full width at half maximum (FWHM) and improved peak intensity attenuation.