Xue Dongbai, Deng Xiao, Dun Xiong, Wang Jun, Wang Zhanshan, Cheng Xinbin
Appl Opt. 2024 Mar 10;63(8):2065-2069. doi: 10.1364/AO.513766.
Laser interference lithography is an effective approach for grating fabrication. As a key parameter of the grating profile, the duty cycle determines the diffraction characteristics and is associated with the irradiance of the exposure beam. In this study, we developed a fabrication technique amplitude-splitting flat-top beam interference lithography to improve duty cycle uniformity. The relationship between the duty cycle uniformity and irradiance of the exposure beam is analyzed, and the results indicate that when the beam irradiance nonuniformity is less than 20%, the grating duty cycle nonuniformity is maintained below ±2. Moreover, an experimental amplitude-splitting flat-top beam interference lithography system is developed to realize an incident beam irradiance nonuniformity of 21%. The full-aperture duty cycle nonuniformity of the fabricated grating is less than ±3. Amplitude-splitting flat-top beam interference lithography improves duty cycle uniformity, greatly reduces energy loss compared to conventional apodization, and is more suitable for manufacturing highly uniform gratings over large areas.
激光干涉光刻是一种用于制作光栅的有效方法。占空比作为光栅轮廓的关键参数，决定了衍射特性，并与曝光光束的辐照度相关。在本研究中，我们开发了一种制作技术——振幅分割平顶光束干涉光刻，以提高占空比均匀性。分析了占空比均匀性与曝光光束辐照度之间的关系，结果表明，当光束辐照度不均匀度小于20%时，光栅占空比不均匀度保持在±2以下。此外，还开发了一个实验性的振幅分割平顶光束干涉光刻系统，以实现21%的入射光束辐照度不均匀度。所制作光栅的全孔径占空比不均匀度小于±3。振幅分割平顶光束干涉光刻提高了占空比均匀性，与传统的变迹相比，大大降低了能量损耗，更适合于大面积制造高度均匀的光栅。
