Acronym	Definition
B	Birefringent coefficient
CCMI	Core cladding mode interferometer
CFBG	Chirped fiber Bragg grating
CWD	Coupling wavelength dip
DLUWT	Doubly-deposited uniform waist tapered fiber
E	Electric field
eFBG	Etched fiber Bragg grating
FBG	Uniform fiber Bragg grating
FEM	Finite element method
FLRDS	Fiber loop ring-down spectroscopy
FPI	Fabry-Perot interferometer
H	Magnetic field
HBF	High birefringence fiber
HB-PCF	High birefringence photonic crystal fiber
Hc	Critical magnetic field
HC-PCF	Hollow-core photonic crystal fiber
LFPI	Cavity length (FPI)
LPG	Long period grating
LSI	Length of the polarized sensing path
MF	Magnetic fluid
MI	Michelson interferometer
MMF	Multimode fiber
MNF	No-core fiber fused between two multimode fibers
MOF	Micro-structured optical fiber
Ms	Saturation magnetization
MZI	Mach-Zehnder interferometer
n	Refractive index of the material present in the cavity (FPI)
NCF	No-core fiber
ncore	Effective refractive index of the core mode (LPG)
$n_{clad}^i$	Effective refractive index of the ith cladding mode (TFBG)
neff	Effective refractive index of the propagate core mode (FBG)
$n_{eff,clad}^i$	Refractive index of the ith cladding mode at ${\lambda }_{clad}^i$ (TFBG)
$n_{eff,core}$	Refractive index of the core mode at λTFBG (TFBG)
$n_{eff,core}^i$	Refractive index of the core mode at ${\lambda }_{clad}^i$ (TFBG)
nfast	Effective refractive index of the fast mode (SI)
nMF	Refractive index of the magnetic fluid
ns	Saturated value of the refractive index of the MF
nslow	Effective refractive index of the slow mode (SI)
n 0	Refractive index of the magnetic fluid under magnetic field lower than critical magnetic field
OPD	Optical path difference (MZI)
PCF	Photonic crystal fiber
PMF	Polarization maintaining fiber
PML	Perfectly matched layer
PS	Phase shift
RIMC	Refractive index matched coupling
SI	Sagnac interferometer
SMF	Single mode fiber
SMS	Single mode-multi mode-single mode
SNS	Single mode-no-core-single mode
SPR	Surface plasmon resonance
T	Temperature
TCF	Thin core fiber
TFBG	Tilted fiber Bragg grating
UV	Ultraviolet
α	Fitting parameter (Langevin function)
εMF	Dielectric constant of the magnetic fluid
${\theta }_{TFBG}$	Tilt angle of the grating planes related to the perpendicular of the fiber axis (TFBG)
θ 1	Angle between the polarization direction of counterpropagating beams and the corresponding fast axes of two HBF sections (SI)
θ 2	Angle between the fast axes of the two HBF sections (SI)
θ 3	Angle between the polarization direction of counterpropagating beams and the corresponding fast axes of two HBF sections (SI)
λ	Optical signal wavelength
λB	Reflected Bragg wavelength (FBG)
λi	Center wavelength of the ith attenuation band
λTFBG	Resonance wavelength of the core mode (TFBG)
${\lambda }_{clad}^i$	Resonance wavelength of the ith cladding mode (TFBG)
Λ	Grating period (FBG)
ΛFPI	Spectral modulation period (FPI)
${\Lambda }_{LPG}$	Grating period (LPG)
Λ TFBG	Grating period along the axis fiber (TFBG)
φFPI	Phase of the reflected optical signal (FPI)
φSI	Phase (SI)
χ	Electric susceptibility