Proceedings Article | 21 November 2007
Proc. SPIE. 6724, 3rd International Symposium on Advanced Optical Manufacturing and Testing Technologies: Design, Manufacturing, and Testing of Micro- and Nano-Optical Devices and Systems
KEYWORDS: Silica, Laser energy, Photons, Electrons, Single photon, Laser ablation, Microopto electromechanical systems, Micromachining, Pulsed laser operation, Absorption
Silica is a good material of MOEMS, however, it is difficult to be micro-processed to form a complicated appearance.
Introduced in this paper is process analysis of fluorine (F2) 157-nm laser micro-ablating silica. The interaction and
mechanism of ablative photo decomposition between the photons of 157-nm laser and silica are discussed in detail. To
test 157-nm silica ablating effect, the profile of micro holes on the end cross section of silica photonic crystal fiber (PCF)
was employed under the exposure of 157-nm beam, to quantitatively analyze the ablating depth and degree. The results
show that under 7.9eV photon energy of 157-nm laser, the defect formations in silica are accumulated to produce a large
quantity of free electrons. Meanwhile, the dopants in silica fiber or glass considerably reduce the breakdown threshold.
Because the rate of single-photon absorption outclasses the rate of multi-photon absorption, it can be inferred that the
mechanism of interactions between 157-nm laser and silica is a process of single-photon absorption of electron-avalanche.
The actual ablating velocity 210nm/pulse showed that the 157-nm laser could be absorbed strongly by silica
material. It also illustrated that there did be thermal process during the ablation, however, because the velocity of damage
caused by ablating was very fast, the heat was therefore limited. A good quality of ablating result could be ensured.
