Design of diamond-shape photonic crystal fiber polarization filter based on surface plasma resonance effect

A novel plasmonic polarization filter based on the diamond-shape photonic crystal fiber(PCF) is proposed. The resonant coupling characteristics of the PCF polarization filter are investigated by the full-vector finite-element method. By optimizing the geometric parameters of the PCF, when the fiber length is 5 mm, the polarization filter has a bandwidth of 990 nm and an extinction ratio(ER) of lower than -20 dB. Moreover, a single wavelength polarization filter can also be achieved, along with an ER of -279.78 dB at wavelength 1.55 μm. It is believed that the proposed PCF polarization filter will be very useful in laser and optical communication systems.     

高非线性光子晶体光纤深紫外超连续谱的研究

光子晶体光纤作为光学非线性良好介质,对超连续谱产生具有重要作用。深紫外超连续谱光源在许多应用中有急切的需求,然而由于实验条件和光纤参数等方面的影响,利用高非线性光子晶体光纤产生深紫外(<280 nm)超连续谱的报道较少。通过理论和实验研究了高非线性光子晶体光纤在深紫外区的频率变换,并分析其产生的物理机理。使用钛宝石飞秒激光器将实验室自制的光子晶体光纤在反常色散区泵浦,研究了不同泵浦功率和泵浦波长对深紫外区超连续谱的影响,结果表明：泵浦波长固定为860 nm时,深紫外频率光谱展宽范围随泵浦功率的增加而逐渐展宽;泵浦功率固定为0.4 W时,泵浦波长的增加不仅展宽超连续谱范围而且极大的提高了深紫外区光谱的转换效率。当泵浦波长为870 nm,泵浦功率为0.4 W,实验所用光子晶体光纤长度为1.45 m,零色散波长为825 nm时,光子与色散波的交叉相位调制使深紫外基模超连续谱扩展到最短波长212 nm。     

全固双层芯色散补偿光子晶体光纤的研究与设计

为了补偿光纤色散对高速信号传输的限制,提出一种全固双层芯色散补偿光子晶体光纤.首先对该光纤模式耦合特性进行理论分析,然后利用多极法进行模拟计算,得到该光纤包层结构参数与色散值以及相位匹配波长之间的关系,并对其规律进行研究.通过优化光纤结构参数,得到在1 550nm处,色散值达到-32 620ps/(nm·km)、损耗为0.29dB/km、与标准单模光纤的熔接损耗为4.77dB的色散补偿光纤.该光纤可补偿1 910多倍长度的SMF-28单模光纤的色散,补偿能力远大于常规色散补偿光纤.与空气孔-石英结构色散补偿光子晶体光纤相比,全固色散补偿光子晶体光纤具有易制备、易与传统通信光纤熔接等优点.     

Single-polarization single-mode hollow-core negative curvature fiber with nested U-type cladding elements

Hollow-core negative curvature fibers (HC-NCFs) have become one of the research hotspots in the field of optical fiber because of their potential applications in the data and energy transmissions. In this work, a new kind of single-polarization single-mode HC-NCF with nested U-type cladding elements is proposed. To achieve the single-polarization single-mode transmission, we use two different silica tubes in thickness, which satisfy the resonance and anti-resonance conditions on the U-type cladding elements and the cladding tubes, respectively. Besides, the elliptical elements are introduced to achieve good single-mode performance. By studying the influences of the structure parameters on the propagation characteristics, the optimized structure parameters are obtained. The simulation results show that when the wavelength is fixed at 1550 nm, the single-polarization single-mode transmission is achieved, with the polarization extinction ratio of 25749 and minimum high-order mode extinction ratio of 174. Furthermore, the confinement loss is only 0.0015 dB/m.     

Broadband tunable Raman soliton self-frequency shift to mid-infrared band in a highly birefringent microstructure fiber

Raman soliton self-frequency shifted to mid-infrared band(λ 2 μm) has been achieved in an air-silica microstructure fiber(MF). The MF used in our experiment has an elliptical core with diameters of 1.08 and 2.48 μm for fast and slow axis. Numerical simulation shows that each fundamental orthogonal polarization mode has two wide-spaced λZDW and theλZDW pairs located at 701/2110 nm and 755/2498 nm along the fast and slow axis, respectively. Using 810-nm Ti:sapphire femtosecond laser as pump, when the output power varies from 0.3 to 0.5 W, the furthest red-shift Raman solitons in both fast and slow axis shift from near-infrared band to mid-infrared band, reaching as far as 2030 and 2261 nm. Also, midinfrared Raman solitons can always be generated for pump wavelength longer than 790 nm if output pump power reaches0.5 W. Specifically, with pump power at 0.5 W, the mid-infrared soliton in slow axis shifts from 2001 to 2261 nm when the pump changes from 790 nm to 810 nm. This means only a 20 nm change of pump results in 260 nm tunability of a mid-infrared soliton.