Rockwell David A, Shkunov Vladimir V, Marciante John R
Raytheon Space and Airborne Systems, 2000 East El Segundo Boulevard, PO Box 902 El Segundo, California 90245, USA.
Opt Express. 2011 Jul 18;19(15):14746-62. doi: 10.1364/OE.19.014746.
A new class of optical fiber is presented that departs from the circular-core symmetry common to conventional fibers. By using a high-aspect-ratio (~30:1) rectangular core, the mode area can be significantly expanded well beyond 10,000 μm2. Moreover, by also specifying a very small refractive-index step at the narrow core edges, the core becomes "semi-guiding," i.e. it guides in the narrow dimension and is effectively un-guiding in the wide mm-scale dimension. The mode dependence of the resulting Fresnel leakage loss in the wide dimension strongly favors the fundamental mode, promoting single-mode operation. Since the modal loss ratios are independent of mode area, this core structure offers nearly unlimited scalability. The implications of using such a fiber in fiber laser and amplifier systems are also discussed.
提出了一种新型光纤，它不同于传统光纤常见的圆形纤芯对称性。通过使用高纵横比（约30:1）的矩形纤芯，模场面积可以显著扩展到远超10000μm²。此外，通过在窄纤芯边缘指定非常小的折射率阶跃，纤芯变为“半波导”，即在窄维度上波导，而在毫米级的宽维度上有效无波导。宽维度上由此产生的菲涅尔泄漏损耗的模式依赖性强烈有利于基模，促进单模工作。由于模式损耗比与模场面积无关，这种纤芯结构提供了几乎无限的可扩展性。还讨论了在光纤激光器和放大器系统中使用这种光纤的影响。
