Yang Li, Xue Lin-Lin, Li Cheng, Su Jue, Qian Jing-Ren
Department of Electronic Engineering and Information Science, University of Science and Technology of China, Hefei, Anhui 230027, China.
Opt Express. 2011 Jan 31;19(3):2251-6. doi: 10.1364/OE.19.002251.
Based on the adiabatic coupling principle, a new scheme of a broadband circular polarizer formed by twisting a high-birefringence (Hi-Bi) fiber with a slowly varying twist rate is proposed. The conditions of adiabatic coupling for the adiabatic polarizer are first identified through analytical derivations. These conditions are easily realized by choosing a reasonable variation of the twist rate. Moreover, the bandwidth of the polarizer is able to be directly determined by the twist rates at the two ends. Finally, the broadband characteristics of the polarizer are demonstrated by simulations. It is also shown that the performance of the polarizer can be remarkably improved by accomplishing a multi-mode phase-matching along the grating or by using of the couplings of the core mode to lossy modes.
基于绝热耦合原理，提出了一种通过以缓慢变化的扭转率扭转高双折射（Hi-Bi）光纤形成宽带圆偏振器的新方案。首先通过解析推导确定了绝热偏振器的绝热耦合条件。通过选择合理的扭转率变化，这些条件很容易实现。此外，偏振器的带宽能够直接由两端的扭转率确定。最后，通过仿真展示了偏振器的宽带特性。还表明，通过沿光栅实现多模相位匹配或利用芯模与损耗模的耦合，可以显著提高偏振器的性能。
