Thermal behavior of Bragg gratings formed in germanosilicate fiber (original) (raw)
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Thermal Stability of Bragg Gratings Written in N-Doped- Silica-Core Fibers
AbstTact: The results of thermal tests of high-temperature Bragg gratings written in a nitrogen-doped-silica-core fiber are preented. The gratings were produced by the conventional teaique using an ArF excimer laser and a phase mask at various exposure regime: show that they can withstand heating up to 900•‹C. The possible physical mechanisms responsible for thermal decay of the gratings are analyzed. Based on these results, the grating written in this type of fibers is potential to be integrated in fiber sensor system, in order to develop a high temperature sensor.
A study of regenerated gratings produced in germanosilicate fibers by high temperature annealing
Optics Express, 2011
In light of recent proposals linking structural change and stresses within regenerated gratings, the details of regeneration of a seed Type-I Bragg grating written in H 2 loaded germanosilicate fiber annealed at high temperatures (~900°C) are systematically explored. In particular, the influence of the strength of the grating, the effect of GeO 2 doping concentration and the annealing conditions on regeneration are studied. We show that the role of dopants such as Ge and F contribute nothing to the regeneration, consistent with previous results. Rather, they may potentially be detrimental. Strongest regenerated gratings with R ~35% from a 5mm seed grating could be obtained in fibres with the lowest GeO 2 concentrations such as standard telecommunications-compatible grade fibre.
Thermal stabilization of Type I fiber Bragg gratings for operation up to 600°C
Optics Letters, 2010
The thermal stability of Type I gratings is increased by postthermal tuning of the grating. Optimization of the procedure leads to gratings that can withstand temperatures as high as 600°C. Aging tests lead to lifetime predictions as high as 25 years with Ͻ3 dB reduction at 400°C. Single exponential relaxation is observed. Above 800°C regeneration is obtained.
Journal of Lightwave Technology, 2004
Accelerated-aging studies of chirped Bragg gratings written in deuterium-loaded germano-silicate fibers were carried out using isothermal and continuous isochronal anneal methods. The master aging curve obtained from the isothermal decay is explained using the Arrhenius-rate-model-based equation. An empirical polynomial function was used to fit the continuous isochronal anneal data. The estimated attempt frequency () values from the two anneal methods were found to agree well within error. Further, the model-based calculations were found to predict postanneal long-term behavior of the gratings extremely well. Implications of the two anneal methods to accurately predict the thermal stability of chirped fiber Bragg gratings are discussed in light of rapid and reliable qualification of different types of gratings written in different fibers. Index Terms-Chirped fiber Bragg gratings (CFBGs), isochronal anneal, isothermal anneal, long-term reliability, thermal stability. Nirmal K. Viswanathan, photograph and biography not available at the time of publication.
Applied Optics, 2003
The thermal decay of a type I fiber Bragg grating written at 248 nm in boron-germanium codoped silica fiber was examined in terms of its reflectivity and Bragg wavelength change. In addition to the decay in reflectivity, which was observed, a shift in Bragg wavelength over the temperature range considered was seen. A mechanism for the decay in the reflectivity was developed and modeled according to a power law, and the results were compared with those from the aging curve approach. The wavelength shift was simulated by modification of the power law, which was also found to fit well to the experimental data. Temperature-induced reversible and irreversible changes in the grating characteristics were observed and considered to be a means to predict the working lifetime of the grating at comparatively low temperatures. Accelerated aging was also reviewed and compared in terms of reflectivity and Bragg wavelength shift. It was shown that the temperature-induced irreversible shift in the Bragg wavelengths could not be predicted by use of the isothermal decay of the refractive-index modulation. The results were discussed within the framework of the current theoretical approaches for predicting the stability of gratings of this type.
Enhanced type IIA gratings for high-temperature operation
Optics Letters, 2004
The inscription of type IIA fiber Bragg gratings in standard boron-codoped germanosilicate fiber has been demonstrated to show marked differences from that reported in the literature. These gratings were subjected to high temperatures, and their decay behavior was evaluated. Gratings resistant to heat up to 800 ± C for a moderate length of time are demonstrated.
Fibre Bragg Gratings, towards a Better Thermal Stability at High Temperatures
Physics Procedia, 2015
Regenerated fibre Bragg gratings (RFBG) are obtained by heating an original seed grating until its reflection practically vanishes, which is followed by the growth of a new reflection band. Advantages of RFBG for sensing purposes are the longer lifetime and higher thermal stability at higher temperatures, as they have been observed to survive temperatures in the range 1300-1500 °C. The thermal stability of the RFBG permits several applications not attained by standard Bragg gratings.
High-temperature type IIa gratings in 12-ring photonic crystal fibre with germanosilicate core
Journal of the European Optical Society: Rapid Publications, 2008
The inscription of efficient Bragg gratings (> 20 dB) in 12-ring photonic crystal fibre with a germanosilicate doped core without the need for hydrogen loading using 193 nm is demonstrated. We show the characteristic rollover from type I grating to type IIa -the first observation of a type IIa grating in structured optical fibre. The type IIa grating is shown to survive up to 700 • C before any degradation in transmission or reflection takes place.
H-Bearing species migration during UV writing of Bragg gratings in germanosilicate optical fibers
Journal of Non-Crystalline Solids, 2007
Bragg gratings (BG) have been written in H 2 -loaded Ge-doped preform plates by means of CW 244 nm-laser light. H-bearing absorbance profiles have been performed along the BG longitudinal axis by means of FTIR absorption micro-spectroscopy. It has been observed that the higher the UV writing time or power, the higher the OH species average concentration but the lower the OH species modulation amplitude along the Bragg gratings axis. It is suggested that OH species migrates from the bright UV fringes towards the dark ones during BG writing. Thus, these diffusing species contribute mainly to the mean index and not to the modulation index.