Alimohammadian Ehsan, Lammers Kim, Alberucci Alessandro, Djogo Gligor, Jisha Chandroth P, Nolte Stefan, Herman Peter R
Opt Express. 2022 Feb 14;30(4):5360-5375. doi: 10.1364/OE.437591.
The formation of volumetric nanogratings in fused silica by femtosecond laser pulses are shown to afford new opportunities for manipulating the physical shape and tailoring the optical properties of the modification zone by harnessing unconventional beam shapes. The nanograting assembly was observed to rigorously follow the beam elongation effects induced with conical-shaped phase fronts, permitting a scaling up of the writing volume. Detailed optical characterization of birefringence, dichroism, and scattering loss pointed to flexible new ways to tune the macroscopic optical properties, with advantages in decoupling the induced phase retardation from the modification thickness by controlling the conical phase front angle. Further insights into an unexpected asymmetric response from Gaussian beams modified with concave and convex phase fronts have been provided by nonlinear propagation simulations of the shaped-laser light.
飞秒激光脉冲在熔融石英中形成体积纳米光栅，通过利用非常规光束形状，为操纵物理形状和定制改性区域的光学特性提供了新机会。观察到纳米光栅组件严格遵循由锥形相位前沿引起的光束伸长效应，从而实现写入体积的扩大。对双折射、二向色性和散射损耗的详细光学表征指出了调整宏观光学特性的灵活新方法，通过控制锥形相位前沿角度，在将诱导相位延迟与改性厚度解耦方面具有优势。通过对整形激光的非线性传播模拟，进一步深入了解了用凹面和凸面相位前沿改性的高斯光束的意外不对称响应。
