Tuning etch selectivity of fused silica irradiated by femtosecond laser pulses by controlling polarization of the writing pulses----Shanghai Institute of Optics and Fine Mechanics

Circular polarization may be advantageous to linear polarization in the fabrication of two-dimensional (2D) and 3D structures due to the independence of electric vector with writing direction, which leads us to investigate the fabrication of microchannels with circularly polarized laser with particular attention. Researchers at State Key Laboratory of High Field Laser Physics——Shanghai Institute of Optics and Fines Mechanics (SIOM/China) report on experimental study on chemical etch selectivity of fused silica irradiated by femtosecond laser with either linear or circular polarization in a wide range of pulse energies.[JOURNAL OF APPLIED PHYSICS 109, 053114 (2011)]

They have experimentally investigated the characteristics of polarization-dependent etch selectivity in fused silica within a wide range of pulse energies. The relationship between etch rates and pulse energies typically shows three characteristic regions. Particularly, our result reveals that the increase of the areas occupied by the etchresistant material, which is more resistant to etching in HF acid than the etch-friendly material, is responsible for the rapid decreasing of etch rate in the high energy region. We also demonstrate the advantage of using circularly polarized femtosecond laser beam for fabricating complex microfluidic structures, by which the uniform etch rate of microchannels written along different directions can be obtained.