Femtosecond-laser-encoded distributed-feedback color center laser in lithium fluoride single crystals

Abstract

Laser-active F 2 centers were produced in lithium fluoride ͑LiF͒ at a concentration of 2 ϫ10 18 cm Ϫ3 by irradiating focused femtosecond ͑fs͒ laser pulses from a mode-locked titanium sapphire laser ͑wavelength ϳ800 nm, emission pulse duration ϳ100 fs). This technique was used to write waveguides embedded in LiF crystals. A refractive index change estimated from a guide propagation method was approximately ϩ1% at a wavelength of 633 nm. Refractive index-modulated volume-type gratings were also encoded inside LiF crystals by a single interfered fs laser pulse. The distributed feedback laser structure was fabricated using the gratings thus encoded, which exhibited a room-temperature F 2 -color center laser oscillation at 707 nm. This demonstrates a DFB color center laser operating at room temperature utilizing photon written, permanent Bragg gratings.

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

“…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.…”

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

“…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.…”

Progress in ultrafast laser processing and future prospects

“…Ultrafast laser processing has been extensively applied to fabricate 3D photonic devices such as optical couplers and splitters [84], volume Bragg gratings [85], diffractive lenses [86], Mach-Zehnder interferometers (MZIs) [87], and waveguide lasers [88,89]. Such photonic devices rely on the writing of 3D optical waveguides that can be easily inscribed in transparent materials such as glass, crystalline materials, and polymers by inducing permanent refractive index changes in the focal volumes of tightly focused ultrafast laser pulses [90].…”