Adjusting resonance wavelengths of long-period fiber gratings by the glass-structure change

Morishita, K.; Kaino, Akihiro

doi:10.1364/ao.44.005018

Cited by 27 publications

(22 citation statements)

References 9 publications

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“…Possible mechanisms for refractive index modulation in the CO 2 -laser-induced LPFGs could be attributed to residual stress relaxation, [73][74][75]99 glass densification, 71,72,100,101 and/or physical deformation, 19,20,[23][24][25][26][27][68][69][70] depending on the types of the employed fibers and on the practical fabrication techniques. A few methods have been demonstrated to measure the refractive index modulation in the CO 2 -laser-induced LPFGs.…”

Section: Refractive Index Modulationsmentioning

confidence: 99%

“…71,72,100,101 For an unannealed fiber or a fiber annealed at a temperature lower than about 380°C, glass densification, resulting in an increase in the refractive index, plays the dominant role. 72 For a fiber annealed at a higher temperature than about 400°C, however, glass volume increase, resulting in a decrease in the refractive index, becomes more important.…”

Section: B Glass Structure Changesmentioning

confidence: 99%

“…[73][74][75]99 For the CO 2 -laser-induced LPFGs in the boron-doped fibers with small residual stress, on the contrary, the resonance wavelength shifts toward the longer wavelength with the increase in the laser exposure dose due to the positive index modulation resulting from glass densification. 71,72,100,101 …”

Section: B Glass Structure Changesmentioning

confidence: 99%

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Review of long period fiber gratings written by CO2 laser

Wang

2010

Journal of Applied Physics

220

134

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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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Section: Refractive Index Modulationsmentioning

confidence: 99%

Section: B Glass Structure Changesmentioning

confidence: 99%

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Review of long period fiber gratings written by CO2 laser

Wang

2010

Journal of Applied Physics

220

134

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“…the displacement of the core with respect to its normal central position in the fibre, as the origin of the grating formation [3], the same structural relaxation implies an increase of the coupling strength (the core-cladding refractive index difference increases). Note, however, that the LP 11 mode was initially over-coupled (the product of the coupling constant at the wavelength of the resonance centre and the grating length was larger than π/2) while the LP 12 and LP 13 modes became over-coupled during the first 20 h of annealing [4]. In Fig.…”

Section: Resultsmentioning

confidence: 94%

Investigation of the long-term stability of arc-induced gratings heat treated at high temperatures

Rego

Caldas

Иванов

et al. 2011

Optics Communications

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“…Therefore, in this case all resonances were overcoupled. In [5] it can be seen that the strength of some resonances increases whereas others decrease during annealing. Regarding the N-doped fibre, the overcoupled resonances shift towards lower wavelengths and their strength also decreases.…”

mentioning

confidence: 99%

Annealing of arc-induced gratings at high temperatures

Rego

2009

Electron. Lett.

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Long period gratings arc-induced in different types of fibre were annealed at 10008C for 24 h. During the annealing, the spectrum of the gratings written in Ge-doped fibres shifted towards longer wavelengths whereas an opposite shift was observed for gratings written in Ge-free fibres. A discussion on the mechanisms responsible for that behaviour is presented.Introduction: In recent years, optical-fibre-based sensors have become a market of increasing demand, since owing to their intrinsic properties they offer clear advantages over the conventional ones. It is irrefutable that high-temperature sensors are of great importance and, since the appearance of UV-induced fibre Bragg gratings, much effort has been put forward from the scientific community in order to increase their high-temperature resistance. The electric arc technique is among the few techniques able to produce gratings that can withstand temperatures of the order of 10008C. In past years, the subject of arc-induced gratings and their applications was intensively investigated, namely, long period fibre gratings (LPFGs) were inscribed in different types of fibre, their temperature behaviour was investigated up to 12008C and distinct behaviour was observed for Ge-doped and Ge-free fibres [1]. It was also demonstrated that arc-induced gratings can withstand temperatures of 12008C for short periods. Annealing experiments in the temperature range 900 -11008C, concerning gratings arc-induced in the SMF-28 fibre, were also conducted for a few hours [2]. In this Letter, we present results on the effect of annealing on gratings arc-induced in Ge-doped and Ge-free fibres at 10008C for 24 h.

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Adjusting resonance wavelengths of long-period fiber gratings by the glass-structure change

Cited by 27 publications

References 9 publications

Review of long period fiber gratings written by CO2 laser

Review of long period fiber gratings written by CO2 laser

Investigation of the long-term stability of arc-induced gratings heat treated at high temperatures

Annealing of arc-induced gratings at high temperatures

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