High pressure H2 loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO2 doped optical fibres

This paper presents a systematic review of long period fiber gratings (LPFGs) written by the CO2 laser irradiation technique. First, various fabrication techniques based on CO2 laser irradiations are demonstrated to write LPFGs in different types of optical fibers such as conventional glass fibers, solid-core photonic crystal fibers, and air-core photonic bandgap fibers. Second, possible mechanisms, e.g., residual stress relaxation, glass structure changes, and physical deformation, of refractive index modulations in the CO2-laser-induced LPFGs are analyzed. Third, asymmetrical mode coupling, resulting from single-side laser irradiation, is discussed to understand unique optical properties of the CO2-laser-induced LPFGs. Fourthly, several pretreament and post-treatment techniques are proposed to enhance the efficiency of grating fabrications. Fifthly, sensing applications of the CO2-laser-induced LPFGs are investigated to develop various LPFG-based temperature, strain, bend, torsion, pressure, and biochemical sensors. Finally, communication applications of the CO2-laser-induced LPFGs are investigated to develop various LPFG-based band-rejection filters, gain equalizers, polarizers, and couplers.

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“…5,122 Hydrogen loading are also found to enhance the writing sensitivity of the CO 2 -laser-induced LPFGs. 16,123 As shown in Fig.…”

Section: Hydrogen Loadingmentioning

confidence: 99%

Review of long period fiber gratings written by CO2 laser

Wang

2010

Journal of Applied Physics

220

134

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“…Index matching the core layer enables the UV-written waveguides to exhibit a circular-mode profile and low coupling loss to standard telecom fiber [8]. Prior to UV exposure, the sample is loaded with molecular deuterium at a pressure of 190 bar until saturation to increase the photosensitivity [9].…”

Section: Methodsmentioning

confidence: 99%

Variable optical attenuator fabricated by direct uv writing

Svalgaard

Færch

Andersen³

2003

J. Lightwave Technol.

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“…Hydrogen loading is presumed to catalyze the absorption both because of the presence of a nearby OH transition 44 and because it may modify the germanium sites in such a way that they become oxygen deficient and increase the 242-nm transition probability. Both these catalytic effects may demand initial activation and therefore be facilitated by heat treatment.…”

Section: ͑4͒mentioning

confidence: 99%

Ultraviolet-light-induced processes in germanium-doped silica

Kristensen¹

2001

Phys. Rev. B

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A model is presented for the interaction of ultraviolet ͑UV͒ light with germanium-doped silica glass. It is assumed that germanium sites work as gates for transferring the excitation energy into the silica. In the material the excitation induces forbidden transitions to two different defect states which are responsible for the observed refractive index changes. Activation energies ͓1.85Ϯ0.15 eV and 1.91Ϯ0.15 eV͔ and rates ͓(2.7Ϯ1.9) ϫ10 13 Hz and (7.2Ϯ4.5)ϫ10 13 Hz͔ are determined for thermal elimination of these states. Good agreement is found with experimental results and new UV-induced effects are predicted.

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High pressure H2 loading as a technique for achieving ultrahigh UV photosensitivity and thermal sensitivity in GeO2 doped optical fibres

Cited by 610 publications

References 6 publications

Review of long period fiber gratings written by CO2 laser

Review of long period fiber gratings written by CO2 laser

Variable optical attenuator fabricated by direct uv writing

Ultraviolet-light-induced processes in germanium-doped silica

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