飞秒激光刻蚀透射式石英玻璃光栅工艺研究

Preparation of Transmission Quartz Glass Grating via Femtosecond Laser Etching

透射式玻璃光栅可简化光学系统结构,降低调制难度和成本,在紧凑型微小型分光仪和光谱系统中应用广泛。因玻璃材料脆、硬等特点,传统加工技术已无法满足现代工业日益增长的需求。采用波长为1040 nm、重复频率为100 kHz、脉冲宽度为388 fs的飞秒激光刻蚀透射式石英玻璃光栅,重点研究了激光功率P、扫描速度v、重复扫描层数N对石英玻璃光栅刻痕宽度和深度的影响。此外,使用氦氖激光器(波长为632.8 nm)对已刻蚀石英玻璃光栅样品进行衍射效率测试,利用CCD记录光栅衍射图样,通过灰度重心法得到其衍射效率。在实验中,当激光功率为442 mW,扫描速度为380 mm/s,重复扫描层数为10时,刻蚀的光栅刻痕宽度d约为5.67μm,光栅周期D约为8.17μm,测得该石英玻璃光栅的0级、-1级和+1级衍射效率分别为24.98%、31.80%和31.04%。

The transmissive glass grating is commonly used in compact micro spectrometers and spectroscopy systems which can simplify the structure of optical system and reduce the complexity and expense of modulation.Traditional manufacturing methods have been unable to meet the increasing demands of modern industry due to the brittle and hard characteristics of glass materials.The transmission quartz glass gratings were etched using a femtosecond laser with wavelength of 1040 nm,repetition rate of 100 kHz,and pulse width of 388 fs.And the effects of laser power P,scanning speed v,and repeated scanning layer N on the etching depths and widths of quartz glass gratings have been investigated.Furthermore,the diffraction efficiency of the etched quartz glass grating sample was measured using a helium-neon laser(wavelength:632.8 nm).The grating diffraction pattern was recorded by a CCD,and the diffraction efficiency was calculated using the gray-scale center of gravity method.In the experiment,under the condition that laser power was 442 mW,scanning speed was 380 mm/s,and scanning times was 10,the etched grating width d was 5.67 μm and the grating period D was 8.17 μm.The testing results show that the zero-order,positive first-order and negative first-order diffraction efficiency of the quartz glass grating are24.98%,31.80% and 31.04 %,respectively.