Photoinduced processes in Sn-doped silica fiber preforms

Chiodini, N.; Ghidini, S.; Палеари, А.; Brambilla, Gilberto; Pruneri, Valerio

doi:10.1063/1.1330749

Cited by 14 publications

(10 citation statements)

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“…8 It has been shown that photosensitivity in tin silicate is due to structural reorganization of the Sn-doped network promoted by coordination changes at Sn defect sites. 9 Although sodium increases the average coordination around the Sn atom ͑up to 6͒ and decreases the percentage of Sn atoms in a substitutional position, nevertheless, the absolute number of Sn atoms with coordination 4 and 2 ͑typical of Sn-oxygen-deficient centers͒ is believed to be higher than in tin silicate, thus showing an overall enhanced photosensitivity, as previously observed in Ref. 5.…”

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confidence: 69%

Photosensitive properties of a tin-doped sodium silicate glass for direct ultraviolet writing

Milanese

Ferraris

Menke

et al. 2004

Applied Physics Letters

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Articles you may be interested inEr:Yb-doped oxyfluoride silicate glass waveguide amplifier fabricated using femtosecond laser inscription Appl. Phys. Lett. 90, 131102 (2007); 10.1063/1.2716866Low-loss planar and stripe waveguides in Nd 3 + -doped silicate glass produced by oxygen-ion implantation Channel waveguide array in Ce-doped potassium sodium strontium barium niobate crystal fabricated by He + ion implantation Appl.Active waveguide fabrication in erbium-doped oxyfluoride silicate glass using femtosecond pulses

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confidence: 69%

Photosensitive properties of a tin-doped sodium silicate glass for direct ultraviolet writing

Milanese

Ferraris

Menke

et al. 2004

Applied Physics Letters

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“…These structures may be related to the medium range structure of the network, specifically the (SiO 4 ) n rings constituting the silica network. [11][12][13][14] Since compaction is one of the main mechanisms proposed to be involved in the photosensitivity of doped silica, 1,2 one may suppose that photoinduced changes of the populations of rings, with different coordination order, can be responsible for ⌬n; specifically, a photoinduced decrease of high-order rings in favor of loworder rings. Raman features due to low-order rings ͑three-and fourfold rings͒ 11,12 were indeed observed to increase with compaction as a function of neutron irradiation 15 or thermal and mechanical densification.…”

Section: ͑3͒mentioning

confidence: 99%

Mechanisms responsible for the ultraviolet photosensitivity ofSnO2-doped silica

2001

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Tin-doped silica samples were prepared by the sol-gel method. Optical absorption and electron paramagnetic resonance measurements were carried out before and after exposure to 266-nm pulsed radiation from the fourth harmonic of the Nd-YAG ͑yttrium-aluminum-garnet͒ laser. The laser-induced change of refractive index was analyzed at different power densities ͑from 1 to 6ϫ10 7 W/cm 2 , 6-ns pulse duration͒ and exposure times. Positive changes of the refractive index up to 4ϫ10 Ϫ4 were observed. The presence and the consequent laser-induced bleaching of the 5-eV absorption band due to oxygen deficient centers, does not appear relevant, since good positive photosensitivity was observed in samples without detectable absorption at this energy.Exposure of silica-based glasses to ultraviolet ͑UV͒ radiation causes a change of the refractive index of the material. 1 This effect is currently studied for applications in optical devices for fiber-optics telecommunications. 2 Optical filtering and other more complex signal processing functions can be implemented in optical fibers or planar waveguides by exposing the material to uv radiation patterns generating modulated changes of refractive index. It was demonstrated that GeO 2 doping of silica, usually employed to produce the core of commercial optical fibers, has a role in this photosensitivity. 1,2 Other kinds of doping are investigated to enhance this property. 1 In particular, recent works showed that SnO 2 doping can give rise to strong and thermally stable photosensitivity. 1,3,4 However, it is not clear whether the microscopic mechanisms involved are those proposed to be responsible for the photosensitivity of GeO 2 -doped silica photoconversion of optically active defects induced by doping and structural compaction of the doped network. 1,2 Contemporaneously to these works, we investigated SnO 2 -doped silica produced by the sol-gel method in order to find the compositional domain compatible with the introduction of diluted tin atoms in Si sites. 5,6 In this paper, we present the results we have obtained on SnO 2 -doped silica samples from the sol-gel method, where Sn substitutional dilution has been achieved. The analysis of the kinetics of the refractive index change vs power density and exposure time gives evidence to two types of mechanisms in substitutional SnO 2 -doped silica, one which involves two-photon processes.Silica xerogels were prepared with a tin content between 0.4 and 0.5 mol%, by the sol-gel method employing hydrolysis of tetraetyl ortosilicate Si͑OEt͒ 4 and dibutyl tin diacetate. 5 Samples were treated at 1050°C by a very slow thermal program comprising a ramp of 4°C/h in vacuum between 450 and 950°C, obtaining complete densification at 1050°C. Samples were then characterized by means of uv absorption spectroscopy ͑Varian Cary 50͒. The indication of the presence of doping-related oxygen deficient centers ͑ODC's͒ was obtained from the 5-eV absorption band. This band arises from twofold-coordinated -Si-cation sites in pure silica, and -Ge-or -Sn-site...

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“…The higher and narrower the energy density of states ͑high E p and low T 0 ͒, the higher the grating thermal stability. Even if ⌬n in SS fibers is given by structural changes, 17,18 the same mathematical formalism accurately describes the grating decay. In our formulation g 0 (E) can be assumed to a͒ Electronic mail: gb2@orc.soton.ac.uk represent the energy distribution of the modified structure.…”

Section: Fiber Bragg Gratings With Enhanced Thermal Stabilitymentioning

confidence: 99%