Hollow waveguides for extreme ultraviolet light and soft X ray

本项目的目的是研制用于真空紫外光和软X射线的柔性、高效的光波导。我们提出了真空中空芯光波导，它在真空、紫外光和软X射线区几乎是高度透明的。真空紫外光用中空铝纤维的降损研究采用MOCVD工艺在玻璃毛细管内侧沉积铝薄膜，优化了沉积前处理条件。结果是，由于铝膜内部光滑，导致的散射损耗很小，所以可以制作出传输损耗低的空芯光波导。真空紫外远距离光谱分析系统的研制利用铝包覆柔性中空纤维研制了一种紫外区远距离光谱分析系统。单色光通过中空光纤传输到目标，反射光被收集并传输回光电倍增管。一束中空纤维也被用作输送介质。提出了一维光子带隙结构的中空光纤，利用包层的光子带隙对光进行限制的多层包层中空光纤。通过对光纤中传输模式的分析，设计了优化的多层结构。提出了在外层沉积多层膜后取下芯棒的制作工艺。软X射线光波导的研制利用中空光纤束制作了软X射线准直光学元件。制备了在软X射线区具有高反射率的内镀镍的中空纤维，并与玻璃毛细光学器件的传输特性进行了比较。

The purpose of this project is to develop flexible and highly-effective waveguides for vacuum ultraviolet light and soft x ray. We propose hollow optical waveguides with vacuum hollow core which is almost highly transparent in vacuum ultraviolet and soft x ray regions.1. Loss reduction of hollow aluminum fibers for vacuum ultraviolet lightIn fabrication process for deposition of aluminum thin film on the inside of glass capillary tubing by using MOCVD process, the conditions for deposition pretreatment were optimized. As a result, hollow waveguides with low transmission losses are fabricated because of smoothness of inner aluminum film which induces little scattering losses.2. Development of remote spectroscopy system in vacuum ultravioletA remote spectroscopy system for ultraviolet wavelength region was developed by using a flexible hollow fibers with aluminum inner coating. Monochromated light is delivered by a hollow fiber to the target and reflected light is collected and transmitted back to photomultiplier. A bundled hollow fiber is also used for delivery media.3. Hollow optical fiber with one-dimensional photonic bandgap structureA hollow fiber with multilayered cladding which confine light by using the photonic bandgap of the cladding were proposed. From analysis of transmitted modes in the fiber, the optimized multilayer structure was designed. Fabrication process using a mandrel which is removed after deposition of multilayer on the outside was also proposed.4. Development of soft x-ray waveguideA collimating optics for soft x ray was fabricated by using a bundled hollow optical fibers. Hollow fibers with inner nickel layer which provides high reflection in soft x-ray region were fabricated and the transmission characteristics were compared with those of glass capillary optics.