Abstract
A novel temperature sensor designed on stimulate Brillouin scattering fast light in liquid-filled photonic crystal fibers is proposed. The time advancement and the Brillouin frequency shift of fast light are simulated according to the three-wave coupling equations of stimulate Brillouin scattering, and the temperature sensing characteristics of the fast light in liquid-filled hexagonal photonic crystal fibers with three different air filling factors are simulated from 20 °C to 70 °C by using the full-vector finite element method. The alcohol-filled photonic crystal fibers exhibit rather sensitive responses to temperature. With temperature varying from 20 °C to 70 °C, the variation of the effective mode area is 2.75 µm at the air filling factor of 0.6, the Brillouin frequency shift is about 11 GHz and its average modification is 1.15 MHz. The time advancement increases with the rise of temperature, its increment can reach up to 4.53 ns at the air filling factor of 0.6 and the pump power of 60 mW, the temperature sensitivity of the time advancement is 0.272 ns/°C.
Highlights
Stimulate Brillouin scattering (SBS), a nonlinear interaction between light wave and acoustic wave, can induce Stocks wave and anti-Stocks wave during transmission [1]
8ΩB p s where Ep, Es and ρ are the amplitudes of the pump wave, the stokes wave and the acoustic wave respectively, n g is the group refractive index, c is the speed of light in vacuum, α is the attenuation coefficient of the photonic crystal fiber (PCF), γe is the electrostriction constant, ωp and Ω are the angular frequencies of the pump wave and the acoustic wave respectively, ΓB is the full width at half maximum of Brillouin absorption spectra or gain spectra and is the reciprocal of the photon life, ΩB is the Brillouin frequency shift which is the frequency difference between the pump wave and the Stokes light, ε0 is the dielectric constant in vacuum
Some parameters including the effective mode area, the Brillouin frequency shift, the SBS threshold value pump power and the SBS fast light parameters such as the time advancement, the pulse broadening factor and the group velocity are simulated for different temperature and different AFF in filled PCF
Summary
Stimulate Brillouin scattering (SBS), a nonlinear interaction between light wave and acoustic wave, can induce Stocks wave and anti-Stocks wave during transmission [1]. The fast or slow light via SBS can be realized in a relative short fiber, which can be used for sensing by adjusting the structure or filling gas or liquid or solid into the air holes of the PCF. Reported systematic experimental characterizations of the SBS in passive 1060 nm SMFs using a highly sensitive optical heterodyne method with a narrow linewidth CW (continuous wave) laser operating at a wavelength of 1064 nm It can be seen from this literature that the research on SBS temperature sensing is mainly based on refractive index of PCF, because the transmission characteristics of light changes with the various refractive indexes of the filled liquid induced by varying temperature, and the previous research focused on SBS slow light. This research will provide a valuable theoretical reference for designing novel temperature sensors based on fast light via SBS in optical fibers
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