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1.
Properties of All-Solid Square-Lattice Photonic Bandgap Fibres   总被引:1,自引:0,他引:1       下载免费PDF全文
Properties of all-solid square-lattice photonic bandgap fibres are studied for the first time to the best of our knowledge. Using the plane-wave expansion method and finite element method, we investigate the mode, effective area, confinement loss and dispersion of such fibres. The simulation results demonstrate that the proposed effective mode area of all-solid square-lattice photonic bandgap fibres is 1.25 times larger than triangular-lattice ones and the confinement loss of the fibres is no more than 0.1 dB/m within the bandgap.  相似文献   

2.
A new structure of highly birefringent honeycomb photonic bandgap fibres (PBGFs), including an elliptical air hole in its solid core, is proposed and analysed by using full vectorial plane wave expansion method. From the numerical results it is confirmed that the proposed PBGF. has birefringence of the order of 10^-3. Moreover, there are two single-polarization single-mode ranges at varying normalized wavelength, in one of which only the slowaxis mode exists, and in the other only the fast-axis mode exists, which has not been achieved in index-guiding photonic crystal fibres so far.  相似文献   

3.
We introduce PBGFs with the cladding made of our newly designed quasi-hexagonal air holes and demonstrate how it actually operates. This cladding structure is introduced for the first time to the best of our knowledge, and is realized by making use of the hydrofluoric acid's corrosive properties. The fibre corrosion can be accurately controlled, thus opening us the gate for the design and fabrication of new PB. GFs with more complex and more efficient cladding structures. Numerical results and actual simulations indicate that PBGFs built with this cladding structure have improved b~dgap properties and guiding bands as wide as 500 nm have been theoretically reached. Using the same method, we have also been able to design two other types of PBGFs with improved cladding structure.  相似文献   

4.
Hollow core's inner surface coating in a photonic bandgap fibre (PBCF) is investigated by means of finite element method. The coat material and thickness-dependence dispersion curve and group velocity dispersion are numerically studied. The coating with materials of low index or small thickness will rise up the dispersion curve but will not induce surface modes. However, coating with materials of high index or big coat thickness will induce surface modes and avoided-crossings. By varying coat material's refractive index and thickness, the appearances of surface modes and avoided-crossings can be changed. It is found that the avoided-crossing can enormously enlarge the negative dispersion which can find applications in dispersion compensation. We numerically achieve a negative dispersion as large as -21416.15ps/nm/km. The results give a physical insight into the propagation properties of PBGFs with the hollow core coated by a layer of material and are of crucial significance in the applications of PBGF coating.  相似文献   

5.
We propose a fluid sensor based on transmission dip caused by mini stop-band in photonic crystal slabs. Simulation results show that this novel type of sensors has large detective range (more than 1.5) and relative high sensitivity (4.3×10^-5 in certain conditions). The central frequency and bandwidth of the mini stop-bands depend on the structure parameters of PC waveguides, which makes it possible to optimize the detective range and detective sensitivity.  相似文献   

6.
By introducing an adjustment waveguide besides the incident waveguide, zero-dispersion slow light with wide bandwidth can be realized due to anticrossing of the incident waveguide mode and the adjustment waveguide mode. The width of the adjustment waveguide (W2) and the hole radii of the coupling region (r') will change the dispersion of incident waveguide mode. Theoretical investigation reveals that zero dispersion at various low group velocity vg in incident waveguide can be achieved. In particular, proper W2 and r' can lead to the lowest vg of 0.0085c at 1550 nm with wide bandwidth of 202 GHz for zero dispersion.  相似文献   

7.
Using the tunable pump pulses with about lOO fs pulse duration and 1064 nm central wavelength; the polarization-, wavelength- and power-dependent anti-Stokes lines are generated and modulated simultaneously in a polarization-maintaining photonie crystal fiber (PM-PCF) with two zero-dispersion wavelengths. By accurately controlling the polarization directions, the wavelength and the power of the pump pulse in the fiber anomalous region close to the second zero-dispersion wavelength of the PM-PCF, the output anti-Stokes pulse spectra can be tuned between 563 nm and 603 nm, which is in good agreement with the theoretical simulation. The color conversion of the mode image from yellow to orange is also observed with the different polarization pump pulses. These results can be attributed to the combined interaction between the fiber birefringence (including linear- and nonlinear- birefringence) and dispersion, and are attributed to phase-matching parametric four-wave mixing.  相似文献   

8.
We present a design of double cladding nearly zero dispersion flattened nonlinear photonic crystal fiber (PCF) with the core consisting of seven missing holes. The dispersion of the designed PCF fluctuates from -0.28 to 0.29 ps·km^-1·nm^-1 in the range of 1.35-1.795μm and the dispersion slope is -0.0038 ps·km^-1·nm^-2at 1.55μm. Due to its small air-hole to air-hole pitch in the inner cladding, the effective mode area is 6.48μm2 and the effective nonlinearity V is as high as 13.78 W^-1 km^-1 at 1.55μm. Two layers of air-hole rings in the outer cladding ensures the loss of the fundamental mode to be 2.9 dB/km at 1.55μm and two more air-hole rings can further reduce the fundamental mode's loss to the level of 4.2 ×10^-3 dB/km.  相似文献   

9.
A highly efficient W3 Y-branch filter in a two-dimensional photonic crystal slab with triangular lattice of air holes is designed and fabricated, and its transmission properties are measured. By accurately adjusting the size of the resonant cavities, the minimum wavelength spacing of 7 nm between two channels is realized. The corresponding resonant wavelengths of the two cavities agree well with the calculated ones. This implies that this kind of fiIter may be promising in integrated wavelength division multiplexing system.  相似文献   

10.
In this paper the dispersion properties and confinement loss of hollow-core photonic bandgap fibers (PBGFs) based on a square lattice (SL) with rounded square air-holes was investigated for the first time, by using a full-vector finite element method (FEM). The waveguide group velocity dispersion (GVD) curves with different core diameter D, air hole size d, rounded diameter dc and hole pitch Λ are presented. The influence of the number of cladding rings on dispersion and confinement loss were also calculated. It was found that as Λ or d increases, the width of PBG becomes wider, and that D and the number of cladding rings have a smaller influence on waveguide GVD. The ratio between bandgap width and central wavelength in our simulation is about 38.1%, which is larger than that of hollow-core PBGFs with triangular lattice (TL) (∼25%). By simulation, the desired zero dispersion wavelength or desired dispersion slope could be obtained by properly choosing the value of dc or Λ. Compared to TL PBGF, at least nine cladding rings is needed to achieve the confinement loss less than 0.1 dB/m for future application.  相似文献   

11.
We propose a scheme of optical one-way transmission by using one-dimensional photonic crystals (PhCs) with diffraction gratings on one side. The one-way transmission is realized by making the PhC opaque to the zeroth diffraction order and transparent to another propagating (in air) diffraction order. For such a structure with 10-period PhC, 93% of the incident energy passes through when an electromagnetic wave impinges from one side, and the transmittance decreases to the order of 0.001% as the electromagnetic wave illuminates from the other side.  相似文献   

12.
The transmission properties of one-dimensional photonie crystals (1DPCs) containing anisotropic metamaterials are theoretically studied. It is shown that the 1DPCs can possess a similar zero average index (zero-n) gaps, the edges of zero-~ gap are weakly dependent on the incident angles, scale length and the polarization of the electromagnetic wave. When an impurity is introduced, a defect mode appears inside the zeron gap with a very weak dependence on incident angles and sealing. It is found that in such photonic crystals, a transmitted Gaussian pulse with its carrier frequency lying in the lower gap edge, in the defect mode and in the bandgap, can experience a positive or negative group delay and hence a subluminal, ultra.slow or superluminal propagation with small distortions. These properties of the photonic crystals have potential applications in the transfer of information.  相似文献   

13.
A kind of high birefringence SF6 soft glass photonic crystal fiber (HBSF6-PCF) is proposed. The properties of birefringence, dispersion, nonlinear coefficient and the transmission characteristics are studied by the multipole method and the adaptive split-step Fourier method. The numerical results show that the birefringence and the nonlinear coefficient reach the orders of 10^-2 and 10^-1, respectively. In addition, the HBSF6-PCFs can generate very smooth supercontinuum spectra when illuminated with femtosecond pulsed light of 1064 nm. It is found that up to 800nm spectral width (evaluated at -5dB from the peak) is achieved. Therefore, the advantage of the HBSF6-PCFs is such that a high birefringence, a high nonlinearity and a smooth supercontinuum are perfectly combined in them.  相似文献   

14.
邓新华  刘念华 《中国物理快报》2007,24(11):3168-3171
We study the transmission of one-dimensional photonic crystals consisting of single-negative permittivity and single-negative permeability media by using transfer matrix method. A pair of transmission modes is found in the gap. The transmission modes are dependent only on the ratio of the thicknesses of the two alternating layers. The separation of a pair of transmission modes can be tuned by varying the thickness of the defect layer or the ratio of thicknesses of the two alternating layers.  相似文献   

15.
Propagation of electromagnetic waves in one-dimensional plasma dielectric photonic crystals, the superlattice structure consisting of alternating plasma and dielectric materials, is studied theoretically using transfer matrix method. Numerical calculation is presented for plasma-air finite and infinite periodic structures. The results of photonic band gap characteristics are discussed in terms of plasma density, plasma width, and number of unit cells (N).  相似文献   

16.
By carrying out the two ideas of asymmetrical confinement and asymmetrical response into the photonic crystal (PC) structures that contain two or more nonlinear defects, we find that significantly unidirectional transmission can beachieved while the transmission for the positive launch direction maintains at large values. Our analyses are supported by the simulation results based on the finite-difference time-domain technique.  相似文献   

17.
Light propagation through a coupled-defect waveguide with a 63.5° bend in a two-dimensional (2D) photonic crystal is investigated. The waveguide modes are non-degenerate monopole state and dipole defect state of a square lattice for two different branches. To increaze the transmission in the bending waveguide, we propose a method to rotate the localized state by introducing a cavity. The higher coupling efficiency and transmission shift. new type defect with a sheared square rod into coupled in the bending waveguide are obtained with proper shear  相似文献   

18.
A new double-layer grating template is designed to reduce the out-of-band loss as much as 1.8dB when the loss of LPo3 reaches 10.2 dB. Meanwhile, we propose a method to remove the sidelobes in the transmission spectra by the adjustment of the thickness of pressure plates. The plate-thickness-induced shift of resonant wavelength and the attenuation of loss peak intensity when removing sidelobes can be modified by the fibre distance and contact point on the pressure plates.  相似文献   

19.
A novel woodpile lattice structure is proposed. Based on plane wave expansion (PWE) method, the complete photonic band gaps (PBGs) of the novel woodpile three~dimensional (3D) terahertz (THz) photonic crystal (PC) with a decreasing symmetry relative to a face-centred-tetragonal (fct) symmetry are optimized by varying some structural parameters and the highest band gap ratio can reach 27.61%. Compared to the traditional woodpile lattice, the novel woodpile lattice has a wider range of the filling ratios to gain high quality PBGs, which provides greater convenience for the manufacturing process. The novel woodpile 3D PC will be very promising for materials of THz Junctional components.  相似文献   

20.
To design and calculate the zero-dispersion wavelength is one of the important aspects for highly nonlinear photonic crystal fibres. By using the air filling fraction f defined as f = ( 6d) / ( 2π∧ ) here for the cladding effective index, and the step effective index model, the relationship between the properties of chromatic dispersion and the two different structures has been analysed. It is pointed that the variation of the zero dispersion wavelength is insensitive to the core diameter change in one range of core diameter D, while keeping the air filling fraction f constant. In the other range of core diameter D, the photonic crystal fibres have the best nearly-zero ultraflattened dispersion. These properties are significant to the design of chromatic dispersion and zero dispersion wavelength in photonic crystal fibres.  相似文献   

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