The very high dispersive dual-core photonic crystal fiber is analyzed by the full-vector finite element method. The
dependence of the phase-matching wavelength (PMW) and the full width at half-maximum (FWHM) on the refractive
index of the doped inner core, the diameter of air holes and the hole pitch is demonstrated. The dispersion value is as
large as -1427 ps/(nm km) and the effective mode area of the fundamental mode, 82.06 um2 are obtained.
A highly negative dispersion photonic crystal fibre with less germanium doped core and central index dip is numerically
investigated by fully vectorial finite element method. By adjusting the pitch, the depths and radius of the central index
dip and the diameter of six small air holes in the third ring, Highly negative dispersion value (-1325.5ps/nm.km) and
large mode effective area (71.4um2) DCPCF around the wavelength of 1.55μm is obtained.
A fully vectorial effective index method and multiple-cladding method (FVEIM&MCM) is developed for modeling
photonic crystal fibers. Large negative dispersion photonic crystal fibers can be designed by changing the diameters of
the first, second and third ring of air-holes.
Highly nonlinear fibers with nearly zero flattened dispersion over a wide band range has very wide applications in future
high-capacity, all-optical networks. Because of its flexibility of structure design and much larger index contrast between
the core and effective cladding than the conventional fibers, photonic crystal fibers (PCFs) are becoming to be an
attractive candidate to form this kind of highly nonlinear fibers. Based on quantitative analysis on the effect of the
difference of hole-sizes between the first ring and the other's, and the effect of Ge-doped concentration in the core region
on the PCF's dispersion curve, a new way to design PCF with high nonlinear coefficient and nearly zero flattened
dispersion is proposed. Based on this, a PCF is designed, which has dispersion values between ±0.8ps/nm/km over
S+C+L wavelength bands, and the dispersion slope of 0.005ps/nm2/km, nonlinear coefficient of 46.6W-1km-1 at 1.55μm.
Through introducing two sizes of hole in the cladding of PCF, a kind of highly birefringent two-mode photonic crystal
fiber (PCF) is proposed. Modal properties are analyzed numerically by the plane wave expansion method. Numerical
results demonstrate that only two-mode, i.e. LP01 and LP11even can propagate in the wavelength range from 500nm to
1890nm in the two-mode PCF which is nine times as wide as that in elliptical core fibers. The theory of highly
birefringence two-mode PCF for constituting fiber sensor is also discussed. According to the structure proposed, we
successfully fabricate the highly birefringent two-mode PCF with stack-drawing technique and gas-inert pressurization
control at furnace temperature 1900°C and gas-inert pressure 900pa. They could extend significantly the application
range of these two-mode devices and open up new possibilities.
Some PCF fabrication techniques are discussed. Effects of draw conditions on the capillaries and the geometry of the final photonic crystal fiber (PCF) are investigated experimentally. The cross-sectional hole structure can be adjusted to a certain extent by controlling the parameters such as the temperature, the feed and draw speed or combinations of these. Since the improvement is limited and hardly can a satisfactory fiber be obtained, the inert gas pressurization method is introduced. It is testified feasible and effective in tuning the geometry of the final PCF and PCFs of good uniformity are fabricated experimentally.
A method for judging mode cutoff in photonic crystal fibers (PCFs) with non-uniform holes
by analyzing the break phenomena of the mode field radius during the increasing of
wavelength is brought forward. And three kinds of PCFs with different structure are analyzed
and discussed in detail using this new method.
In this presentation, the universal structure of one-dimensional photonic crystal (1-D PC) is constructed, and its optical transmission properties are analyzed by transfer matrix method (TMM). A case that there are two kinds of medium as a period is studied in detail. It is concluded that the reflectivity in photonic band-gap (PBG) increases with the increasing of periodical number, and the bandwidth of PBG has direct relation with the difference between two kinds of dielectric constant, three methods for extending PBG are discussed. When defect layer is inserted, a defect mode appears in the PBG. The concept of optimal periodical number is presented, and it is found that this optimal periodical number is only relative to the ratio of dielectric constant (K). Using multi-objective optimization method, we educe the curve and equation relation between optimal periodical number and K for the first time. In addition, the change in the number of defect mode with the variation of the defect layer's thickness is analyzed, and it is explained by the theory of F-P cavity.
Photonic crystal fiber (PCF) has aroused growing interest over the past few years becauce PCFs exhibit many unusual properties, especially an endlessly single mode and highly tunable dispersion. Polyethylene have distinguish advantages such as the real part of dielectric constant keep constant in the frequency range from 0.1THz to 2THz that the material dispersion contribute little to total dispersion, and the imaginary part of the dielectric constant is close to zero in THz frequencies that the material loss is low. This offer a new possibility of constituting polyethylene PCF for low loss and low dispersion THz waveguide. In this paper, propagation properties of polyethylene PCF in THz frequencies are analyzed by full-vector model. Numerical results demonstrate that effective index of fundamental mode decreases with frequency decreasing and near zero-dispersion can be obtained over a wide frequency region.
The splice losses between PCF and SMF and between two PCFs with different structure are analyzed based on mode field radius of the fibres, respectively. And the effect of each structure parameter on the splice loss was discussed.