飞秒激光在光敏玻璃内制作微孔

Femtosecond Laser Fabrication of Microholes in Photosensitive Glass

用20倍显微物镜将波长为775nm的飞秒激光聚焦在光敏玻璃(FOTURAN)内部,通过纵向写制模式由表面以下500μm曝光至表面,并结合热处理和在浓度8%的氢氟酸超声溶液中腐蚀50min,在FOTURAN内部制作了直径为几十μm的微孔.利用光学和扫描电子显微镜分析发现微孔具有圆形横截面和清晰边缘,目前得到的深宽比大约为7.通过在宽范围内改变入射激光能流(2.3～36.2J/cm2)和写制速度(100～1000μm/s),研究了这两项飞秒激光入射参量对制作微孔的影响.发现写制速度对制作微孔直径影响较小,而利用相对低的入射激光能流曝光可得到较大深宽比的微孔,并且在此情形下制作微孔的横截面更圆,璧面光滑度更高,并分析了原因.

Microholes were fabricated inside a bulk photosensitive glass （FOTURAN） by focused femtosecond laser irradiation at 775 nm wavelength, followed by programmed heat treatment and wet chemical etching in 8% ultrasonic solution of hydrofluoric （HF） acid for 50 minutes. The focused irradiation was performed by femtosecond-laser longitudinal writing geometry,with upward direction from 500μm below the surface. The morphologies of formed microholes were analyzed by optical and scanning electron microscopy. It is observed that microholes with circular cross section and clear edge are obtained inside FOTURAN and their diameters are measured to be several tens microns. The maximal aspect ratio value measure of microholes at 7 is achieved. By varying the average laser fluence in a wide range of 2.3- 36.2 J/cm^2 and the writing velocity in 100-1 000 μm/s, the influences of the incident femtosecond laser parameters on the formation of microholes were experimentally characterized. It is found that the writing velocities hardly affect the microhole diameter,while relatively lower incident laser fluences result in higher aspect ratio,circular cross-section and smoother wall and the possible reason is discussed.