Transmission Bandwidth Tunability of a Liquid-Filled Photonic Bandgap Fiber

A temperature tunable photonie bandgap fiber （PBGF） is demonstrated by an index-guiding photonic crystal fiber filled with high-index liquid. The temperature tunable characteristics of the fiber are experimentally and numerically investigated. Compression of transmission bandwidth of the PBGF is demonstrated by changing the temperature of part of the fiber. The tunable transmission bandwidth with a range of 250nm is achieved by changing the temperature from 30℃ to 90℃.     

Characteristics of Photonic Bandgap Fibres with Hollow Core＇s Inner Surface Coated by a Layer Material

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.     

基于质子交换和刻蚀工艺的体铌酸锂阵列波导光栅

提出一种将质子交换技术和刻蚀技术结合的体铌酸锂波导和器件加工方案,基于质子交换的铌酸锂晶体相变特性改变,降低了质子交换区直接刻蚀难度,结合质子交换的纵向折射率改变和刻蚀波导的横向结构改变,波导尺寸显著降低,采用粒子群算法优化波导尺寸,最小可达2.5μm。基于该工艺方案设计了中心波长为1550 nm、四通道且通道间隔为400 GHz的阵列波导光栅,该阵列波导光栅的传输损耗约为6 dB,相邻通道间串扰均低于22 dB,整体尺寸仅为850μm×620μm,在高密度铌酸锂光子集成互连等场景具有较大的应用潜力。     

Design of Photonic Bandgap Fibre with Novel Air-Hole Structure

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.