Understanding Hole Pattern Formation During Microstructured Optical Fiber Draw

该提案是响应NSF 03-537高速光通信和网络的招标而提交和资助的。微结构光纤，也称为多孔或光子晶体光纤，作为超高容量光通信的关键使能技术具有很强的潜力。例如，空芯光纤具有比标准单模光纤低几个数量级的色散和损耗数值。然而，目前的微结构光纤受到光纤中不均匀的孔尺寸和孔图案引起的高光学衰减（1dB/km）的限制。该方案的重点是了解从预制件拉制的微结构光纤的孔图案分布。这种基本的理解是通过建立预制件的温度分布，粘弹性和表面张力的影响，决定了光纤的中空微结构之间的关系。由于玻璃粘度与温度呈指数关系，轻微的温度变化会显著改变孔的尺寸、位置和稳定性，导致高光学损耗和性能下降。本文将研究空心熔融石英棒的颈缩和稳定性。该模型将提供必要的基本见解，以追求该计划的长期目标，即探索孔图案形成，放置和控制的新方法和条件，并为光纤社区提供强大的数学建模工具，以实现微结构光纤器件和系统的精确模拟。在这项研究中，我们将：（1）在OFS实验室测量和扩展目前有限的高温熔融石英玻璃的红外光学性质;（2）为参与热辐射传输的中空塌陷圆柱体开发综合辐射传热模型;（3）开发能够预测拉制过程中的温度分布、孔形成和稳定性的综合颈缩模型;以及（4）通过OFS实验室进行的绘制实验来广泛验证预测。该项目由化学和运输系统部门的热运输和热处理计划以及设计，制造和工业创新部门的GOALI（学术与工业联系的资助机会）计划联合赞助。

This proposal was submitted and funded in response to solicitation NSF 03-537 High Speed Optical Communications and Networks.Microstructured fibers, also known as holey or photonic crystal fibers, have strong potential as a critical enabling technology for ultra-high capacity optical communications. For example, air-cored fibers have dispersion and loss figures that are orders of magnitude below that of standard single mode fiber. However, current microstructured fibers are limited by high optical attenuation (1 dB/km) caused by uneven hole size and hole patterns in the fiber. This proposal focuses on understanding the hole pattern distribution of microstructured optical fiber being drawn from a preform. This fundamental understanding is achieved by establishing a relationship between the preform's temperature distribution, viscoelastic and surface tension effects that dictate the fiber's hollow microstructure. Since glass viscosity is exponentially dependent on temperature, slight temperature variations can significantly change hole size, placement, and stability, resulting in high optical loss and performance degradation. This proposal will study the neck down and stability of a hollow fused silica rod. This simplifiedmodel will provide necessary fundamental insight to pursue this program's long-term goals, which are to explore new methods and conditions for hole pattern formation, placement and control, and to provide the fiber-optics community with robust mathematical modeling tools to enable accurate simulation of microstructured fiber devices and systems. In this study, we will: (1) Measure and expand currently limited infrared optical properties of high temperature fused silica glass at OFS Laboratories; (2) Develop a comprehensive radiation heat transfer model for hollow collapsing cylinders that participate in thermal radiation transport; (3) Develop a comprehensive neck downmodel capable of predicting the temperature distribution, hole formation and stability during draw; and (4) Extensively validate predictions with draw experiments performed at OFS Labs.The project is being jointly sponsored by the Thermal Transport and Thermal Processing Program of the Chemical and Transport Systems Division and the GOALI (Grant Opportunities for Academic Liaison with Industry) Program of the Design, Manufacturing and Industrial Innovation Division.