Characterization of variable reflectivity of a polarization-maintaining fiber Sagnac mirror for long-distance remote fiber Bragg gratings cavity sensors

Abstract

Variation of broadband reflectivity is experimentally characterized for a polarizationmaintaining fiber (PMF) Sagnac mirror. Theoretical analysis is also demonstrated using the Jones matrices of the PMF Sagnac mirror. Variable reflectivity is useful to enhance the signal performance of a long-distance remote fiber Bragg gratings (FBGs) cavity sensor at a range of tens of km. Controlling both the reflecting bandwidth and partial reflectivity assists the effective multi-wavelength lasing from the linear-type resonance cavity with FBG mirrors at one side and a PMF Sagnac mirror at the other. The FBG sensing signal achieves a high SNR of greater than ∼45 dB due to the cavity mirror effect.

Fabrication of a temperature-insensitive transverse mechanical load sensor by using a photonic crystal fiber-based Sagnac loop

“…An optical fiber Sagnac interferometer (OFSI) has attracted considerable attention from researchers and engineers due to its high performance and numerous flexible applications in sensing [1][2][3][4][5][6][7]. In an OFSI, the two waves counterpropagate along completely identical paths and experience the same loss.…”

Uniform spacing interrogation of a Fourier domain mode-locked fiber Bragg grating sensor system using a polarization-maintaining fiber Sagnac interferometer

“…A fiber Sagnac interferometer based on a PMF is used to generate a comb-fringe spectrum, as shown in the dashed box of figure 1. The comb spacing Δλ peak-peak is inversely proportional to the length and birefringence of the PMF, as follows: $$\mathrm{normal\Delta }{\lambda }_{\text{peak}-\text{peak}}=\frac{{\lambda }^2}{\mathrm{normal\Delta }{n}_{\text{eo}}L}$$ where λ is the operating wavelength, Δn eo is the birefringence and L is the effective length of the PMF [19]. Assuming the PMF has the following parameters, L = 140 cm, λ = 1540 nm, Δn eo = 0.000 38, each comb-fringe peak is separated by Δλ peak-peak ≈ 4.5 nm.…”

“…where λ is the operating wavelength, n eo is the birefringence and L is the effective length of the PMF [19]. Assuming the PMF has the following parameters, L = 140 cm, λ = 1540 nm, n eo = 0.000 38, each comb-fringe peak is separated by λ peak-peak ≈ 4.5 nm.…”

High-Birefringent Fiber Loop Mirror Sensors: New Developments

“…Breakthrough of Hi-Bi FLM configurations 1997 Temperature sensor ; temperature sensing in NIR ; strain sensor (Campbell et al, 1997(Campbell et al, ) 1999 Strain sensor (Campbell et al, 1999) 2004 Temperature PCF sensor (Kim, D. H. & Kang, 2004); temperature insensitivity using PCF (Zhao et al, 2004(Zhao et al, ) 2005 Interrogation system using PCF (Yang et al, 2005); displacement sensor (Liu et al, 2005) 2006 Liquid level sensor (Dong, B. et al, 2006); FBG interrogation system ; LPG/Hi-Bi FLM (Frazao et al, 2006b) 2007 Review of Hi-Bi FLM sensors (Frazao et al, 2007a); strain PCF sensor (Dong, X. Y. et al, 2007;Frazao et al, 2007b) ; chemical etching (Frazao et al, 2007c); concatenated FLM (Frazao et al, 2007d) 2008 Temperature Erbium Hi-Bi fiber (Frazao et al, 2008a); refractive index sensor (Frazao et al, 2008b); multiparameter sensor using side-hole fiber (Frazao et al, 2008c); pressure PCF sensor (Fu et al, 2008); FBG/Hi-Bi FLM (Zhou et al, 2008); current sensor (Marques et al, 2008) 2009 Multiplexing Hi-Bi FLM (Fu et al, 2009); strain and temperature discrimination using two Hi-Bi fibers ); hollow-core PCF sensor (Kim, G. et al, 2009); holey fiber filled with metal indium (Kim, B. H. et al, 2009) 2010 Torsion PCF sensor ; curvature PCF sensor (Gong et al, 2010); pressure-induced SMF ; long distance remote interrogation system (Lee et al, 2010); small core PCF (Andre et al, 2010); intensity strain sensor (Qian et al, 2010); suspended twin-core ; displacement PCF sensor 2011 Hi-Bi FLM with an output port probe ; LPG/Sagnac Loop (Kang et al, 2011); curvature PCF sensor (Hwang et al, 2011); Hi-Bi photonic bandgap Bragg fiber …”

“…Another torsion sensor was done by placing a PCF in a FLM and demonstrated its temperature insensitivity . The variation of reflectivity for long-distance remote FGB cavity sensors using a Hi-Bi FLM was analyzed and demonstrated (Lee et al, 2010).…”