A simple and novel distributed tilted fiber Bragg gratings (TFBGs) based transverse load sensing system using optical
frequency domain reflectometry (OFDR) is proposed and demonstrated for the first time. The transverse load compresses
an elastomer material around the fiber and induces a broadband loss in the spectrum of the TFBG. The additional loss is
directly measured by the return loss spectrum of Fresnel reflection points introduced in the Rayleigh backscattering
trace. With the wavelength sweeping characteristic of OFDR, we realized distributed sensing by interrogating each of the
TFBGs with different wavelengths and observed a minimum crosstalk effect between sensors.
In this letter, we put forward a new kind of polarization-maintaining index-guiding photonic crystal fiber (PM-IG-PCF).
It is made up of a solid silica core, two big circular air holes near the core and a cladding with elliptical air holes. By
making use of a full-vector finite-element method (FEM), we study the modal birefringence and polarization mode
dispersion (PMD) as a function of the normalized wavelength of fundamental modes in the PM-IG-PCF we proposed.
Numerical results show that very high modal birefringence with magnitude of order of 10<sup>-3</sup> has been obtained, which is
higher than the birefringence induced by adding two big air holes near the core or elliptical air holes in cladding
separately. Furthermore, the chromatic dispersion curves of the two orthogonal polarizations for the birefringence PCF
are presented as a function of the normalized wavelength.
Novel highly birefringent photonic bandgap fibers (PBGFs) are obtained by filling high index material in the air holes of total internal reflection birefringent photonic crystal fibers. The effect of filling high-index material on the transmission characteristics has been theoretically investigated. The photonic bandgap has been achieved by using the plane-wave method. Moreover, the polarization mode dispersion (PMD) has been studied by a full-vector finite-element method. Numerical results show that very high PMD with magnitude of order of 10<sup>-10</sup> has been respectively acquired, which is much higher than those of the non-filled fibers. Furthermore, strong coupling between surface modes and the fundamental modes has been found in the bandgap of the birefringent PBGFs.
Tunable photonic bandgap fibers (PBGFs) were theoretically investigated by using the vector plane-wave expansion method and the vector finite element method. The tunable PBGFs are fabricated by filling high index material in the air holes of index-guiding photonic crystal fibers. The wavelength dependence of leaky loss and group velocity dispersion (GVD) has been illustrated. We show the leaky loss in the tunable PBGFs can be strongly depended on the refractive index of filled material due to the photonic bandgap effect. The tunable attenuator which operates at 1550nm is designed based on this PBGFs.
Tunable photonic bandgap fibers (PBGFs) were theoretically investigated by using the vector plane-wave expansion method and the vector finite element method. The tunable PBGFs are fabricated by filling a high-index material in the air holes of index-guiding photonic crystal fibers. The wavelength dependence of leaky loss and group velocity dispersion (GVD) has been illustrated. We show the leaky loss in the tunable PBGFs can strongly depend on the refractive index of filled material due to the photonic bandgap effect. The tunable attenuator which operates at 1550 nm is designed based on this PBGFs.
In this letter, long period gratings fabricated in single-mode microstructure fibers (index-guiding MF and PBG MF) were achieved by putting periodic pressure on the cladding along the fiber length, furthermore, the characteristics of the LPGs were discussed.
We present theoretical analysis of tunable bandgap guidance in virtue of bandgap theory. By means of plane-wave method a novel tunable photonic bandgap microstructure fiber (MF) was investigated by tuning the refractive index of nematic liquid crystal crystal (NLC) filled in the holes of MFs. Moreover, by using a full-vector finite-element method (FEM) with anisotropic perfectly matched layers (PMLs), the dispersion curves of NLC filled MFs have been computed with different value of the refractive index of NLC. Moreover, the leakage loss of the fundamental modes of the NLC filled MFs has been analyzed.
Using a full-vector finite element method, the phase modal birefringence and group modal birefringence to lateral pressure alone slow axis and fast axis versus wavelength in birefringence microstructure fiber was analyzed. In the wave band of our research, 600nm-1700nm, when different direction pressure is applied, the phase modal birefringence (B) and group modal birefringence (G) have different change to wavelength in microstructure fiber. Moreover, the results reveal that the pressure sensitivity of B and G have different change to wavelength when applying different direction lateral pressure. Our research has great signification in designing microstructure fiber and using microstructure fiber in sensing field et.al., especially using in multidimensional sensor.
We present a numerical study of the guidance and amplification properties in an Er<sup>3+</sup>-doped honeycomb photonic bandgap fiber with down-doped core. Our analysis is based on a full-vector plane-wave expansion method and Runge-Kutta iterative algorithm. Overlap integrals between mode profiles and Er<sup>3+</sup>-doped region varies from 0.973 to 0.350 in guiding range of the fiber. The highly efficient amplifier can be designed by using this fiber.