Femtosecond laser micromachining of fibre Bragg gratings for simultaneous measurement of temperature and concentration of liquids

Alemohammad, H. and Toyserkani, E. and Pinkerton, A. J. (2008) Femtosecond laser micromachining of fibre Bragg gratings for simultaneous measurement of temperature and concentration of liquids. Journal of Physics D: Applied Physics, 41 (18): 185101. -. ISSN 0022-3727

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Abstract

This paper is concerned with micromachining of optical fibre Bragg gratings (FBGs) using a femtosecond pulsed laser. The purpose of this work is to increase the sensitivity of FBGs for simultaneous monitoring of the concentration of chemicals and biological liquids and their temperature. A Ti : sapphire regenerative amplifier was utilized to inscribe micro-grooves with widths of 16 and 22 mu m in the cladding of the optical fibres. Due to the core-confined light propagation characteristics of FBGs, their sensitivity to the changes in the index of refraction of the surrounding medium is minimal. However, by creating micro-grooves in the cladding layer, the index of refraction of the surrounding medium becomes effective in the coupling of the propagating core modes. As the index of refraction of liquids depends on the composition and concentration, the FBG with micromachined cladding can provide enough sensitivity to be used in chemical sensing. The performance of the micromachined FBGs was investigated by immersing them in different liquid solutions of polyvinyl butyral (PVB) in ethanol and obtaining their thermal responses. Results showed that the optical response of the micromachined FBGs (i.e. red shift in Bragg wavelength) is different by up to 10% in PVB solutions in ethanol than in ethanol alone. The micromachined FBGs can be used to monitor the concentration as well as the temperature of a solution.

Item Type:
Journal Article
Journal or Publication Title:
Journal of Physics D: Applied Physics
Uncontrolled Keywords:
/dk/atira/pure/core/keywords/engineering
Subjects:
?? engineeringsurfaces, coatings and filmsacoustics and ultrasonicselectronic, optical and magnetic materialscondensed matter physicsta engineering (general). civil engineering (general) ??
ID Code:
59516
Deposited By:
Deposited On:
26 Oct 2012 15:37
Refereed?:
Yes
Published?:
Published
Last Modified:
15 Jul 2024 13:21