Guo Tie-Ying

A New Type of Terahertz Waveguides

A new type of THz waveguides, which employs a solid polyethylene rod as the core and polyethylene tubes in a periodic array of square lattice as the cladding, is proposed. Optical properties of this new THz waveguide, especially in dispersion, confinement loss and single mode property, are investigated in detail with the plane wave expansion method and the beam propagation method. Numerical results demonstrate that the new THz waveguide can reach not only low dispersion but also low confinement loss at single mode propagation. Therefore, the square lattice structure is a better candidate as THz waveguides than the triangular ones.

Investigation on the Fabrication of Photonic Crystal Fibre

Effects of draw parameters, such as drawing temperature and feed speed, on the capillaries and the geometry of the final photonic crystal fibre (PCF) are investigated. Inert gas pressurization is introduced in the preform during the fibre drawing process to finely control the geometry of the PCF so that good uniform in transversal and longitudinal of the final PCF can be realized. Due to the introduction of a special method, the drawing temperature is increased over 1900°C and the strength of the PCF is enhanced.

A simple model for approximate bandgap structure calculation of all-solid photonic bandgap fibre based on an array of rings

A simple model for approximate bandgap structure calculation of all-solid photonic bandgap fibre based on an array of rings is proposed. In this model calculated are only the potential modes of a unit cell, which is a high-index ring in the low-index background for this fibre, rather than the whole cladding periodic structure based on Blochs theorem to find the bandgap. Its accuracy is proved by comparing its results with the results obtained by using the accurate full-vector plane-wave method. High speed in computation is its great advantage over the other exact methods, because it only needs to find the roots of one-dimensional analytical expressions. And the results of this model, mode plots, offer an ideal environment to explore the basic properties of photonic bandgap clearly.

Design of broadband single-polarization single-mode holey fiber

We propose a novel structure of single-polarization single-mode(SPSM) holey fiber designed based on resonant coupling effect. The proposed fiber is able to achieve SPSM operation over an ultra-broad bandwidth as large as 920nm ranging from 1.48µm to 2.4µm, within which only one polarization state of the fundamental mode can be effectively guided. With the aid of six smaller holes around the central core, the effective mode area of the fiber is enlarged and the chromatic dispersion curve is flattened. The numerical results indicate that the proposed fiber achieves nearly zero ultra-flattened dispersion over a wide spectral range and the effective mode area is approaching ∼78µm2 at 1550nm. Moreover, the structure shows superiority in output beam quality owing to the symmetry of the central core region, and also exhibits great modal compatibility with SMF.We propose a novel structure of single-polarization single-mode(SPSM) holey fiber designed based on resonant coupling effect. The proposed fiber is able to achieve SPSM operation over an ultra-broad bandwidth as large as 920nm ranging from 1.48μm to 2.4μm, within which only one polarization state of the fundamental mode can be effectively guided. With the aid of six smaller holes around the central core, the effective mode area of the fiber is enlarged and the chromatic dispersion curve is flattened. The numerical results indicate that the proposed fiber achieves nearly zero ultra-flattened dispersion over a wide spectral range and the effective mode area is approaching ~78μm at 1550nm. Moreover, the structure shows superiority in output beam quality owing to the symmetry of the central core region, and also exhibits great modal compatibility with SMF.

Highly Birefringent Honeycomb Photonic Bandgap Fibre

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 slow-axis 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.

A new method for analyzing mode cutoff in photonic crystal fibers with non-uniform holes

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.

Research on highly nonlinear photonic bandgap fibers

A new type of highly nonlinear photonic bandgap fiber with modified honeycomb lattice is brought forward. Based on full-vector plane-wave method, the structure of bandgaps and the distributions of fundamental mode field are analyzed. Then its nonlinear coefficient is calculated, and the effect of each structural parameter on the nonlinear coefficient is discussed. At last, considering many factors synthetically, we make some optimization design of the structural parameters. It can be concluded that this new type of photonic bandgap fiber can gain the nonlinear coefficient of 30 W−1km−1.