A highly sensitive fiber-optic interferometric sensor based on an all-solid birefringent hybrid photonic crystal fiber (PCF)
is demonstrated for measuring strain and temperature. A strain sensitivity of ~23.8 pm/με and a thermal sensitivity of ~-
1.12 nm/°C are demonstrated in the experiment.
We report the fabrication and characterization of a fiber Bragg grating (FBG) with 870 nm resonance wavelength in a
single-mode TOPAS microstructured polymer optical fiber (mPOF). The grating has been UV-written with the phasemask
technique using a 325 nm HeCd laser. The static tensile strain sensitivity has been measured as 0.64 pm/μstrain,
and the temperature sensitivity was -60 pm/°C. This is the first 870nm FBG and the first demonstration of a negative
temperature response for the TOPAS FBG, for which earlier results have indicated a positive temperature response. The
relatively low material loss of the fiber at this wavelength compared to that at longer wavelengths will considerably
enhance the potential utility of the TOPAS FBG.
Fibre Bragg grating (FBG) sensors have been fabricated in polymer photonic crystal fibre (PCF). Results are presented
using two different types of polymer optical fibre (POF); first multimode PCF with a core diameter of 50μm based on
poly(methyl methacrylate) (PMMA) and second, endlessly single mode PCF with a core diameter of 6μm based on
TOPAS cyclic olefin copolymer. Bragg grating inscription was achieved using a 30mW continuous wave 325nm helium
cadmium laser. Both TOPAS and PMMA fibre have a large attenuation of around 1dB/cm in the 1550nm spectral region,
limiting fibre lengths to no longer than 10cm. However, both have improved attenuation of under 10dB/m in the 800nm
spectral region, thus allowing for fibre lengths to be much longer. The focus of current research is to utilise the increased
fibre length, widening the range of sensor applications. The Bragg wavelength shift of a grating fabricated in PMMA
fibre at 827nm has been monitored whilst the POF is thermally annealed at 80°C for 7 hours. The large length of POF
enables real time monitoring of the grating, which demonstrates a permanent negative Bragg wavelength shift of 24nm
during the 7 hours. This creates the possibility to manufacture multiplexed Bragg sensors in POF using a single phase
mask in the UV inscription manufacturing. TOPAS holds certain advantages over PMMA including a much lower
affinity for water, this should allow for the elimination of cross-sensitivity to humidity when monitoring temperature
changes or axial strain, which is a significant concern when using PMMA fibre.
We have theoretically investigated twin-core all-solid photonic bandgap fibers (PBGFs) for evanescent wave sensing of
refractive index within one single microfluidic analyte channel centered between the two cores. The sensor can achieve
ultrahigh sensitivity by detecting the change in transmission. We find novel features in the sensing characteristics: the
sensitivity is higher at the short wavelength edge of a bandgap than at the long wavelength edge, the effective index of
the odd supermode (nodd) is more sensitive to ambient refractive index change compared with that of the even supermode
(neven).
Access to the requested content is limited to institutions that have purchased or subscribe to SPIE eBooks.
You are receiving this notice because your organization may not have SPIE eBooks access.*
*Shibboleth/Open Athens users─please
sign in
to access your institution's subscriptions.
To obtain this item, you may purchase the complete book in print or electronic format on
SPIE.org.
INSTITUTIONAL Select your institution to access the SPIE Digital Library.
PERSONAL Sign in with your SPIE account to access your personal subscriptions or to use specific features such as save to my library, sign up for alerts, save searches, etc.