19芯碲酸盐玻璃放大光纤的低串扰结构设计及性能仿真

基于空分复用技术的多芯光纤通信核心指标之一是信道串扰,该问题的存在极大地影响着传输距离及信号质量,尤其是在宽带光纤放大系统中。本文重点讨论了弱耦合19芯光纤的串扰问题,同时提出了一种利于多组分碲酸盐玻璃挤压制备的沟槽辅助型19芯光纤,并采用耦合功率理论和有限元法对模型进行了相关性能的数值仿真,系统研究了沟槽尺寸、折射率分布及相关光纤参数对芯间串扰的影响。仿真结果表明,优化设计后的光纤在1550 nm处拥有-156 dB/100 m的低串扰值,可以满足大容量光纤通信用宽带光放大器的应用需求。

PERFORMANCE IMPROVEMENT FOR A WCDMA RADIO OVER FIBER SYSTEM USING DIGITAL PRE-DISTORTER

In this paper,a Radio Over Fiber (ROF) system with a Digital Pre-Distorter (DPD) for WCDMA signal transmission is investigated.A Look-Up Table (LUT) based DPD and a Memory Polynomial (MP) DPD are applied in the ROF link so as to suppress the out-of-band spurious spectrum and improve the transmission performance.The experimental results show that the out-of-band emission due to existence of the third-order Inter-Modulation Distortion (IMD3) is obviously sup-pressed by these two DPD.An Adjacent Channel Power Ratio (ACPR) improvement of 8 dB is ob-tained for a single-carrier WCDMA signal transmission.These two DPD have equal ability in lin-earization of the ROF system for a three-carrier WCDMA signal transmission.There is no apparent memory effects exist in the ROF link.

Spectroscopic Properties and Effect of Radiation Trapping of a New Er^(3+)/Yb^(3+) Co-Doped Tellurite-Silicate Glasses

A new serials of Er^3＋/Yb^3＋ co-doped tellurite-silicate glasses were prepared by the technique of high-temperature mehing. The thermal stability, absorption spectra, emission spectra and upconversion spectra were measured and investigated. It is found that these kinds of glasses have good thermal stability, broad FWHM and large stimulated emission cross-section. The three upconversion emission at 525, 546, 658 nm, corresponding to the ^2H11/2→^4Ⅰ15/2, ^4S3/2→4^Ⅰ15/2 and ^F9/2→^4Ⅰ15/2 transitions of Dr^3＋ ions,

Laser-Induced Phase Transformation in Chalcogenide Glasses Investigated by Micro-Raman Spectrometer

A 488 nm continuous wave （CW） laser was employed in Raman spectrometer to both induce and characterize phase transformation in chalcogenide glasses. Laser-induced Raman inactive changes, structural evolution, and crystallization were observed at laser-irradiated region in GeS2-Sb2S3 glasses. The composition dependence of laser-induced phase transformation was discussed in terms of thermal stability and microstructural modification. It is strongly suggested from these results that fabrication of passive and active chalcogenide glass waveguides, such as refractive index change and nonlinear optical crystal line, is controllable by selecting appropriate glass composition, and convenient by using common CW lasers.

中红外大模场单模全固态硫系光子晶体光纤

针对当前硫系光纤难以同时实现高功率传输与高光束质量的问题,通过COMSOL软件仿真模拟光纤性质,设计出了满足单模传输需要且具有大模场面积的光子晶体光纤(PCF)的结构参数。所设计的光纤在1.5~10μm的波长范围内满足高阶模(LP_(11))与基模(LP_(01))的限制损耗比大于10~2的单模条件,且光纤基模的有效模面积在波长2μm处约为5362μm^(2)。根据仿真模拟的结构参数,探索出新型动、静态蒸馏相结合的技术,制备出高纯硫系玻璃,结合新型的挤压-堆积法,制备出基于全硫系玻璃的全固态大模场单模光子晶体光纤。该光纤在波长1.55μm处的近高斯光能量分布特征验证了其单模特性;同时在弯曲半径为14 cm的1.5 m长的光纤中观察到低弯曲损耗为1 dB,与仿真结果基本一致,表明此全固态光子晶体光纤具有出色的单模传输和抗弯性能,在中红外高能激光传输方面具备一定的应用潜能。