Three-Dimensional Micro- and Nano-Fabrication in Transparent Materials by Femtosecond Laser

Abstract

Femtosecond pulsed lasers have been widely used for materials microprocessing. Due to their ultrashort pulse width and ultrahigh light intensity, the process is generally characterized by the nonthermal diffusion process. We observed various induced microstructures such as refractive-index-changed structures, color center defects, microvoids and microcracks in transparent materials (e.g., glasses after the femtosecond laser irradiation), and discussed the possible applications of the microstructures in the fabrication of various micro optical devices [e.g., optical waveguides, microgratings, microlenses, fiber attenuators, and three-dimensional (3D) optical memory]. In this paper, we review our recent research developments on single femtosecond-laser-induced nanostructures. We introduce the space-selective valence state manipulation of active ions, precipitation and control of metal nanoparticles and light polarization-dependent permanent nanostructures, and discuss the mechanisms and possible applications of the observed phenomena.

Formation and assignment of silver defect centres in phosphate glass induced by femtosecond laser pulses

“…The peak power density of the laser beam irradiated on the sample was estimated to be 8.0 × 10 14 W/cm 2 for Curve 3 and 1.1 × 10 15 W/cm 2 for Curve 4, respectively. For Curve 3, a peak position at 315 nm of the absorption band was in good agreement with that of the X-ray irradiated absorption band (Curve 2), while for Curve 4 the spectrum was dominated by an absorption band at 407 nm that could be ascribed to the surface plasmon resonance (SPR) of the formed silver nanoparticles (Zhao et al, 2004;Shimotsuma et al, 2005).…”

“…It is well-known that irradiation with fs laser pulses as well as X-rays and subsequent annealing at high temperature (~770 K) for 10 min in silver-doped glasses bring about the reduction of Ag + ions to Ag 0 atoms and result in the formation of plasmonic nanoparticles, as observed by means of luminescence, electron spin resonance (ESR) and transmission electron microscopy (TEM) (Zhao et al, 2004;Shimotsuma et al, 2005). Fig.…”

“…Recent advances in high-intensity femtosecond (fs) laser pulses have made it possible to fabricate small noble metal particles such as gold and silver atoms embedded in glasses (Watanabe et al, 2001;Zhao et al, 2004;Shimotsuma et al, 2005) as well as encode various functional microstructures inside transparent materials (Kawamura et al, 2004;Kurobori et al, 2005;Kurobori et al, 2007). As far as silver-doped phosphate glass, Watanabe et al (2001) demonstrated a photosensitivity in soda-alumina-phosphate glass doped with Ag + upon exposure to ultraviolet (UV) fs laser pulses and found the formation of colour centres such as Ag 0 and Ag 2+ in the glass.…”

Assignments and optical properties of X-ray-induced colour centres in blue and orange radiophotoluminescent silver-activated glasses

“…In the case of silver-activated glasses, it is well known that irradiation with fs laser pulses as well as X-rays and subsequent annealing at high temperature (~770 K) for 10 min bring about the reduction of Ag + ions to Ag 0 atoms and result in the formation of plasmonic nanoparticles, as observed by means of luminescence and ESR spectroscopy and transmission electron microscopy (TEM). Measurements taken with such intense fs laser pulses have played a significant role in the evaluation of RPL characteristics in glasses and in the determination of the formation kinetics of related colour centres [10][11][12] . 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 10 Fig.…”

“…In addition, recent advances in high-intensity femtosecond (fs) laser pulses have made it possible to fabricate small noble metal particles [9][10][11] such as gold and silver atoms embedded in glasses as well as encode various functional microstructures inside transparent materials [12][13][14]. In particular, such metal nanoparticles embedded in glasses are expected to 1 2 3 4 5 6 7 8 9 10 11 12 13 14 15 16 17 18 19 20 21 22 23 24 25 26 27 28 29 30 31 32 33 34 35 36 37 38 39 40 41 42 43 44 45 46 47 48 49 50 51 52 53 54 55 56 57 58 59 60 61 62 63 64 65 4 nanoparticles in Ag + -activated phosphate glass without heat treatment was demonstrated for the first time to clarify the origin of a RPL glass dosimeter by highly successive fs laser pulses.…”