基于飞秒激光加工的高阈值高阶贝塞尔光束产生器件

Abstract

Objective The highorder Bessel beam (HOBB) is a special kind of vortex beam that carries orbital angular momentum (OAM) and shows nondiffractive and selfhealing properties. Thus, HOBBs exhibit great application potential in laser micro/nanofabrication, microparticle manipulation, optical illumination, and nonlinear optics. So far, HOBBs have been generated by several methods, such as traditional optical systems, spatial light modulators, and metasurface. These 研究论文 第 43 卷 第 13 期/2023 年 7 月/光学学报 constant spot size over a transmission distance of 4 meters (Fig. 8). It is noteworthy that the zeroprobability LIDT of the prepared optical element is as high as 28. 5 J/cm 2 (6 ns) (Fig. 9), which presents significant benefits in highpower beam shaping applications. ConclusionsIn the present study, a method for fabricating an integrated optical modulation element with a high LIDT is proposed and verified. The nanograting is a subwavelength birefringent structure whose optical axis direction and phase retardance can be modified by the laser polarization direction and processing parameters, respectively. The nanograting with spatially variable optical axis distribution can be written inside the silica glass at different depths. The multilayer cascade structure modulates the phase of the incident beam to generate the target beam . Based on the femtosecond laserinduced nanograting, an integrated HOBB generator with an operating wavelength of 532 nm and topological charge of 4 is fabricated. The test results indicate that the optical field modulation performance of the generator is satisfactory. The HOBB generated by the prepared element carries the specified topological charge and keeps spot size constant over a long nondiffraction transmission distance (4 meters). It is crucial that the LIDT of the prepared optical element is as high as 28. 5 J/cm 2 (6 ns). This method enables the integration of optical elements with distinct functions, providing a novel concept for the integrated preparation of optical elements with high LIDT and complicated optical field modulation.