High-T_g TOPAS microstructured polymer optical fiber for fiber Bragg grating strain sensing at 110 degrees

Abstract

Abstract:We present the fabrication and characterization of fiber Bragg gratings (FBGs) in an endlessly single-mode microstructured polymer optical fiber (mPOF) made of humidity-insensitive high-Tg TOPAS cyclic olefin copolymer. The mPOF is the first made from grade 5013 TOPAS with a glass transition temperature of Tg = 135°C and we experimentally demonstrate high strain operation (2.5%) of the FBG at 98°C and stable operation up to a record high temperature of 110°C. The Bragg wavelengths of the FBGs are around 860 nm, where the propagation loss is 5.1dB/m, close to the fiber loss minimum of 3.67dB/m at 787nm.

Fast and stable gratings inscription in POFs made of different materials with pulsed 248 nm KrF laser

“…Furthermore, the higher moisture absorption capability of PMMA can harm its application in temperature or strain sensing where a humidity cross-sensitivity is undesirable [16]. In order to mitigate the issue of humidity cross-sensitivity, POFs made of cyclic olefin copolymer such as Topas grade 8007 [16,17] and 5013 [18,19] and cyclic olefin homopolymer such as Zeonex 480R [20] can be employed. Gratings inscribed in fiber made of these materials demonstrated a humidity sensitivity at least 30 times lower than that of PMMA POFBGs.…”

“…The low glass transition temperature of Topas 8007 fibers severely limits the range of temperature sensing. In order to combat this, POFs made of another grade of Topas with a T g of 134 °C was demonstrated [18,19]. Another polymer material employed for high temperature and strain sensing is Zeonex 480R, which has a Tg of 138°C.…”

Bandpass transmission filters based on phase shifted fiber Bragg gratings in microstructured polymer optical fibers

“…However, since the first polymer FBG reported in 1999 [22], several promising devices, mainly for the measurement of strain and temperature using step-index fiber and micro-structured fiber have been demonstrated [23][24][25]. Despite of this, for the inscription of the grating, the photosensitivity of the material is important; so far great advances have been done both in doped [26][27][28] and undoped fibers [29], but grating time stability is still an issue if the FBG is not properly annealed [24,30]. Previous literature reports that power density have an effect on time stability of the grating [31] and also a chirped Bragg grating inscribed using an KrF excimer laser at 248nm kept unchanged for 13 weeks [32].…”

Simultaneous measurement of temperature and humidity with microstructured polymer optical fiber Bragg gratings

“…In addition, POFs have a high elastic strain limit with low Young's modulus and are biocompatible, which makes them advantageous for fiber Bragg grating (FBG) based strain and bio-sensing applications [3][4][5][6][7][8] . Some polymers, such as PMMA, are humidity sensitive and strongly absorb water 9 , while other polymers, for instance TOPAS and Zeonex, are insensitive to humidity [10][11][12] . Exploiting such unique and intrinsic properties of POFs, researchers in this area have developed different single parameter POFBG sensors such as strain, temperature, humidity, pressure and soon [13][14][15][16][17] .…”