Formation of two-dimensional periodic microstructures by a single shot of three interfered femtosecond laser pulses on the surface of silica glass

Abstract

Two-dimensional periodic microstructures, including both microholes and micro-orbicular platforms, have been fabricated on the surface of silica glass by a single shot of three interfered femtosecond laser pulses. The three-dimensional structure of a fabricated hexagonal lattice can be revealed by atomic force microscopy. The formation of the microstructure and the dynamic process of the interaction between the femtosecond laser and the silica glass have been discussed.

Holographic Fabrication of Periodic Microstructures by Interfered Femtosecond Laser Pulses

“…10 (b) and agreed well with the simulated results [see Fig. 10 (c)] [16,17]. In experiments, the geometric angles were kept as θ=30 0 and ϕ=35 0 respectively as shown in Fig.…”

“…However, the intensity at the focal point of the femtosecond laser beam where three beams interfere together could reach to 100 TW/cm 2 nearly. Such a high-energy influence within the focal volume ionized the silica glass quickly through the combined action of the avalanche and multiphoton processes [17,35]. A layer of plasma formed on the surface of the silica glass at the time of the laser pulse duration.…”

“…The induced periodic microstructure depicted by an AFM: (d) Energy is 75 J per pulse, (g) Energy is 30 J per pulse, (f) (i) Three-dimensional image of the microstructure of (d) and (g) respectively, (e) (h) The cross section of the microstructure in the direction of black line showed in (d) and (g) respectively subsequent posterior part of the pulse also removed the central plasma very swiftly by means of light pressure, so there is a tiny hole formed in the center of the enhanced spot. However, in the region of the molten liquid, there were two distinct interaction components because of Marangoni effect, thermocapillary and chemicapillary, which resulted from the thermal potential of a temperature gradient and the chemical potential of a compositional gradient, respectively [17,[36][37]. The thermocapillary force moved the molten material outward from the center, while the chemicapillary force moved the molten material toward the center [38][39] as depicted in Fig.…”

“…By increasing the number of beams [16][17][18][19][20] or the double-exposure techniques [40], in principle, two-dimensional (2D) and three-dimensional (3D) periodic patterns can be designed. Although, as stated above, the interference of the three beams [13,[16][17] can create a 1D [13] or 2D [16,17] periodic pattern on the surface of the materials of inside the transparent materials, the complicated optical setup is required for the interference of multiple laser beams, and its precise adjustment is difficult. Kondo et al [18,19] and Si et al [20] have reported the fabrication of the 2D tetragonal lattice by four noncoplanar interfered pulses originating from the single pulse with the aid of the special DBS (diffractive beam splitter).…”

“…Femtosecond laser pulse is also becoming into a powerful tool for microfabrication and micro-machining of various multi-functional structures in dielectric materials through multi-photon absorption because of its high-quality and damage-free processing. Up to now, many highquality material processing techniques have been achieved by using femtosecond laser pulses with the methods of directly writing [1][2][3][4][5][6][7][8][9][10] and holographic fabrication [11][12][13][14][15][16][17][18][19][20][21][22], such as waveguide [1], special diffractive optical elements (DOE) [4][5][6][7][8][9][10], micro-gratings [11][12][13][14][15], and photonic crystals [16][17][18][19][20]. Because multiphoton nonlinear effects play a major role in this process, the resulting change in refractive index or cavity formation can be highly localized only in the focal volume where the fluence is above a certain material dependent threshold, which makes it possible to micro-fabricate devices inside the bulk of transparent materials.…”