Theoretical and experimental investigations have been made of the three-dimensional microchannel fabrication of photostructurable glass by use of a femtosecond (fs) laser. Generally, a microchannel fabricated inside glass by the scanning focal spot of a fs laser perpendicular to the direction of laser propagation assumes an elliptical shape with a cross section of large aspect ratio. We demonstrate that one can greatly reduce the aspect ratio merely by inserting a slit, which is oriented parallel to the laser’s scanning direction, before the focusing lens. Computer simulations show that a more symmetrical pattern is obtained in the vicinity of the focal point with the help of such a slit, owing essentially to a diffraction effect.
© 2003 Optical Society of America
(140.3390) Lasers and laser optics : Laser materials processing
(140.7090) Lasers and laser optics : Ultrafast lasers
(270.4180) Quantum optics : Multiphoton processes
(350.3390) Other areas of optics : Laser materials processing
Ya Cheng, Koji Sugioka, Katsumi Midorikawa, Masashi Masuda, Koichi Toyoda, Masako Kawachi, and Kazuhiko Shihoyama, "Control of the cross-sectional shape of a hollow microchannel embedded in photostructurable glass by use of a femtosecond laser," Opt. Lett. 28, 55-57 (2003)