Properties Of Photonic Crystal Fiber Research Articles

Mode Exciting Properties of Photonic Crystal Fibres with theOptical Field Incident from a Single Mode Fibre

We numerically investigate the mode exciting properties of photoniccrystal fibres by using the beam propagation method when the optical fieldis input from a traditional single mode fibre. The results show thatboth the excited mode spectrum and the coupling-efficiency of eachexcited mode depend on the normalized pitch Ł/λ and thenormalized hole-size Ł/λ. Furthermore, we obtain the boundaryprofile of the optimizing coupling-efficiency for the excitedfundamental mode: the boundary (Ł/λ)* is linear to the boundary(d/Ł)*. All of these will pave the way for smoothingapplications of photonic-crystal fibres, such as splicing and designingphotonic-crystal-fibre functional devices.

Simple models for predicting transmission properties of photonic crystal fibers

AbstractSimple, fast, and efficient 1D models for evaluating the transmission properties of photonic crystal fibers are proposed. Using these models, axial propagation constant, chromatic dispersion, effective area, and leakage loss can be predicted with a reasonable accuracy but much faster than often time‐consuming 2D analytical and numerical techniques and with much less computational resources. It is shown that the results are in good agreement with the published data available in the literature. © 2006 Wiley Periodicals, Inc. Microwave Opt Technol Lett 48: 1286–1290, 2006; Published online in Wiley InterScience (www. interscience.wiley.com). DOI 10.1002/mop.21624

Photonic sensing based on variation of propagation properties of photonic crystal fibres

We report on a low-coherence interferometric scheme for the measurement of the strain and temperature dependences of group delay and dispersion in short, index-guiding, 'endlessly-single-mode' photonic crystal fibre elements in the 840 nm and 1550 nm regions. Based on the measurements, we propose two schemes for simultaneous strain and temperature measurement using a single unmodified PCF element, without a requirement for any compensating components, and we project the measurement accuracies of these schemes.

Ultra-flattened-dispersion selectively liquid-filled photonic crystal fibers

We propose a method to control the chromatic dispersion properties of photonic crystal fibers using the selective hole filling technique. The method is based on a single hole-size fiber geometry, and uses an appropriate index-matching liquid to modify the effective size of the filled holes. The dependence of dispersion properties of the fiber on the design parameters such as the refractive index of the liquid, lattice constant and hole diameter are studied numerically. It is shown that very small dispersion values between 0+/-0.5ps/nm-km can be achieved over a bandwidth of 430-510nm in the communication wavelength region of 1300-1900nm. Three such designs are proposed with air hole diameters in the range 1.5-2.0microm.

Analysis of photonic crystal fibers: Scalar solution and polarization correction

A numerical approach based on the scalar finite element method is applied to analyse the modal properties of photonic crystal fibers having a solid core and a cladding region with either circular or non-circular microstructured holes. A correction which accounts for the polarization effects due to the large refractive index difference between silica materials and air holes is included in the analysis. Numerical results show that the proposed technique is an efficient and accurate alternative to vector ones.

Linear and nonlinear properties of photonic crystal fibers filled with nematic liquid crystals

AbstractWe investigate linear and nonlinear light propagation in the photonic crystal fibers infiltrated with nematic liquid crystals. Such a photonic structure, with periodic modulation of refractive index, which could be additionally controlled by the temperature and by the optical power, allows for the study of discrete optical phenomena. Our theoretical investigations, carried out with the near infrared wavelength of 830 nm, for both focusing and defocusing Kerr-type nonlinearity, show the possibility of the transverse light localization, which can result in the discrete soliton generation. In addition, we present the preliminary experimental results on the linear light propagation in the photonic crystal fiber with the glycerin-water solution and 6CHBT nematics, as the guest materials.

Guiding Properties of Square-lattice Photonic Crystal Fibers

In this paper we have investigated the guiding properties of photonic crystal fibers (PCFs) with a square-lattice of air-holes in the cladding. We have shown numerical results of PCFs with various air hole sizes and hole-to-hole spacings over a wide wavelength range. The group velocity dispersion, effective area and effective refractive index of PCF have been calculated numerically. The waveguide dispersion has greatly affected the group velocity dispersion when hole-to-hole spacing is about <TEX>$1{\mu}m$</TEX>. The effective area is quite flat over the wide spectral range whether the hole-to-hole spacing is large or ratio of diameter to pitch is large. From the field distribution, we found that the field is tightly confined within the core region of PCF when the pitch is <TEX>$3{\mu}m$</TEX> and the air-filling fraction is 0.9.

Influence of Deformation Holes on Properties of PhotonicCrystal Fibres

Deformation of some air holes often occurs during the fabricationprocess of photonic crystal fibres (PCFs). Effects of the location andsize of deformation holes on the properties of actual triangularlattice PCFs are investigated in detail. Numerical results demonstratethat the properties of PCFs, especially birefringence, are sensitive tothe location and size of deformation holes. These would be very helpfulto improve the fabrication technique of the PCF and also offers anefficient way to design high birefringence PCF.

Sequential confocal and multiphoton laser scanning microscopy using a single photonic crystal fibre based light source

A novel approach that simplifies the laser source requirements for confocal and multiphoton laser scanning (CLSM and MPLSM) using the novel dispersion properties of photonic crystal fibre (PCF) is reported. By tuning the fs-pulsed Ti:Sapphire laser to the zero dispersion wavelength of the PCF, the spectral and temporal properties of the source are largely unaffected and hence this source can easily be used for MPLSM. Conversely, by tuning the Ti:Sapphire laser emission wavelength by less than 10 nm to anomalously pump the PCF, the resultant white-light supercontinuum source can perform CLSM. Sequential CLSM and MPLSM of a double-labelled guinea pig detrusor (smooth muscle layer) specimen is described.

Semianalytical approach to short-wavelength dispersion and modal properties of photonic crystal fibers

Photonic crystal fibers made from arbitrary base materials are considered, and a unified semianalytical approach for the dispersion and modal properties is derived that applies to the short-wavelength regime. In particular, the dispersion and the effective index are calculated and compared with fully vectorial plane-wave simulations, and excellent agreement is found. Asymptotic results for the mode-field diameter and the V parameter are also calculated, and from the latter it is predicted that the fibers are endlessly single mode for a normalized airhole diameter smaller than 0.42, independently of the base material.

Dispersion Properties of Photonic Crystal Fiber: Comparison by Scalar and Fully Vectorial Effective Index Methods

The development of analysis and simulation of propagation characteristics of photonic crystal fiber (PCF) using scalar and fully vectorial effective index methods are described. As a result, we report how the fundamental space filling mode, guided mode and dispersion of the PCF depends on its structural parameters like its normalized air hole spacing, center-to-center spacing of the air holes in the photonic crystal or pitch and radius of the unit cell. Normalized frequency parameter Veff as a function of normalized wavelength for various relative air hole sizes is obtained to estimate the dispersion characteristics of PCF. It is observed that wavelength of zero dispersion, ultraflattened dispersion response and high negative dispersion remarkably differ from two different effective index methods.

Progress on low loss photonic crystal fibers

Photonic crystal fibers (PCF) with a silica–air microstructure have received increasing attention in recent years. In this paper, we analyze the loss properties of PCF and report our progress on low loss PCF. We show that the loss performance of PCF is dominated by scattering loss and OH − absorption loss. We show that the PCF scattering loss depends on both the roughness of the hole interior surface and the power distribution in the fiber cross-section. By employing appropriate polishing, etching and dehydration processes, we succeeded in obtaining a PCF with an OH − absorption loss as low as 0.4 dB/km at 1.38 μm and another PCF with a loss of 0.28 dB/km at a wavelength of 1.55 μm, which are the lowest values to the best of our knowledge.

Studies on the dispersion in photonic crystal fiber using the step effective index model

As a precondition , it was presented that the single_mode optical fiber , the dispersion_shift optical fiber and the dispersion_flatten optical fiber can be regarded as the special examples of the index_guiding photonic crystal fiber(PCF) under a determinate condition, when the new step effective index model （SEIM） was used to discuss the chromatic dispersion properties of PCF. The result compared with the experimental data reported in the literature indicated that such a SEIM can be used to uncover more interesting dispersion regimes in PCFs. In particular, the speed of calculation by using the SEIM is very quick. Finally, the dispersion characteristics of the PCF with different air hole diameter d, air hole pitch Λ and the core radius a were also discussed.

Empirical relations for simple design of photonic crystal fibers

In order to simply design a photonic crystal fiber (PCF), we provide numerically based empirical relations for V parameter and W parameter of PCFs only dependent on the two structural parameters - the air hole diameter and the hole pitch. We demonstrate the accuracy of these expressions by comparing the proposed empirical relations with the results of full-vector finite element method. Through the empirical relations we can easily evaluate the fundamental properties of PCFs without the need for numerical computations.

Dispersion properties of square-lattice photonic crystal fibers

In this paper the guiding properties of photonic crystal fibers with a square lattice of air-holes in a silica matrix have been studied for the first time. The dispersion curves of fibers with different hole-to-hole spacing and air-hole diameter have been accurately calculated. Negative values of the dispersion parameter and the dispersion slope have been obtained with a hole-to-hole spacing of 1 microm. A comparison between fibers with square and triangular lattice has been also performed, taking into account the dispersion properties and the effective area in the wavelength range between 1200 nm and 1600 nm.

Modeling of PCF with multiple reciprocity boundary element method

The multiple reciprocity boundary element method (MRBEM) is applied to the modeling of Photonic Crystal Fiber (PCF). With the MRBEM, the Helmholtz equation is converted into an integral equation using a series of higher order fundamental solutions of the Laplace equation. It is a much more efficient method to analyze the dispersion, birefringence and nonlinearity properties of PCFs compared with the conventional direct boundary element method (BEM).

Modal Characteristics of Photonic Crystal Fibers

The modal characteristics of the photonic crystal fibers are analyzed using the reliable and efficient plane wave expansion method. The mode profile, effective index and group velocity dispersion are obtained by solving Maxwell's vector wave equations without any approximation. The zero dispersion condition of a photonic crystal fiber is derived over a wide range of wavelengths. Higher-order modes are also easily found as a by-product of the plane wave expansion method. This method can be used to quickly and accurately design various optical properties of photonic crystal fibers.

Dispersion properties of photonic crystal fibers

AbstractThe dispersion properties of silica‐based photonic crystal fibers (PCFs) are analyzed to obtain: (i) zero dispersion at any wavelength, (ii) nearly zero ultraflattened dispersion, and (iii) a very high negative chromatic dispersion for various designs of PCFs. The influence of normalized air hole size on zero dispersion wavelength is also reported. © 2003 Wiley Periodicals, Inc. Microwave Opt Technol Lett 37: 129–132, 2003; Published online in Wiley InterScience (www.interscience.wiley.com). DOI 10.1002/mop.10845

Dispersion Properties of Photonic Crystal Fibers - Issues and Opportunities

ABSTRACTThe dispersion, which expresses the variation with wavelength of the guided-mode group velocity, is one of the most important properties of optical fibers. Photonic crystal fibers (PCFs) offer much larger flexibility than conventional fibers with respect to tailoring of the dispersion curve. This is partly due to the large refractive-index contrast available in silica/air microstructures, and partly due to the possibility of making complex refractive-index structures over the fiber cross section. We discuss the fundamental physical mechanisms determining the dispersion properties of PCFs guiding by either total internal reflection or photonic bandgap effects, and use these insights to outline design principles and generic behaviours of various types of PCFs. A number of examples from recent modeling and experimental work serve to illustrate our general conclusions.

Leakage properties of photonic crystal fibers

An analysis of the con.nement losses in photonic crystal fibers due to the finite numbers of air holes is performed by means of the finite element method. The high flexibility of the numerical method allows us to consider fibers with regular lattices, like the triangular and the honeycomb ones, and circular holes, but also fibers with more complicated cross sections like the cobweb fiber. Numerical results show that by increasing the number of air hole rings the attenuation constant decreases. This dependence is very strong for triangular and cobweb fibers, whereas it is very weak for the honeycomb one.