nanowires in fibers - a base for mid-IR all-solid cladding hollow core fibers

电磁能量到所需位置的有效传输清楚地代表了任何实际相关光子系统的基本特征。这种引导通常是通过波导（WGs）来实现的，它依赖于将光波横向限制在一个核心内。最突出的WG例子是硅基光纤，它是电信的骨干，主要在近红外（near-IR）波长或可见光下工作。一个特别有趣的光谱域，严重缺乏有效的WG解决方案，是中红外（2.5至25µm）。这个领域是指几乎所有材料的电子跃迁以下的光子能量，从科学和应用的角度来看都是有吸引力的。中红外光谱可以通过分子指纹识别生物、医学和环境科学中的低浓度。中红外光谱也用于爆炸物检测，医疗保健和热成像。重要的气体激光器在中红外波段工作，如二氧化碳激光器——世界上使用最多的激光器。近年来，由于在高谐波产生或基于频率梳的测量中有前景的应用，非线性社区对中红外WGs的强烈需求已经增长。许多目前使用的中红外设备包括复杂的、不可移动的和成本密集的设置，阻碍了许多中红外应用的广泛使用。一个低损耗和灵活的WG解决方案，目前还不存在，将在各个领域产生巨大的影响。在这个名为“纤维中的纳米线：中红外全固体包层空心芯纤维的基础”的项目中，将探索两种具有独特包层结构的新型中红外空心芯纤维。这些全固体包层光纤要么基于无限超材料，要么基于光子带隙效应。这两种结构都将由围绕空芯的全固体包层组成，使这种纤维设计独特。这项研究将导致新的物理效应，并将为超越常规硅纤维的光谱域的新型中红外器件铺平道路。本提案的研究成果是跨学科的，将在生物光子学、超快光学、光谱学和气体激光等各个领域产生影响。

The efficient transportation of electromagnetic energy to desired locations clearly represents an essential feature of any practically relevant photonic system. Such guiding is typically achieved by waveguides (WGs) relying on transversely confining the light wave inside a core. The most prominent WG example is the silica-based optical fiber, which is the backbone of telecommunications and mostly operates at near-infrared (near-IR) wavelengths or in the visible.One particular interesting spectral domain, severely lacking of efficient WG solutions is the mid-IR (2.5 to 25 µm). This domain refers to photon energies below the electronic transitions of almost all materials and is attractive from both the scientific as well as from the application point of view. Mid-IR spectroscopy allows identifying low concentrations by molecular fingerprints in biology, medicine and environmental science. Mid-IR spectroscopy is also employed for explosive detection, within healthcare and for thermal imaging. Important gas lasers operate in the mid-IR such as the CO2-laser - the most employed laser worldwide. A strong demand for mid-IR WGs from the nonlinear community has grown during recent years due to promising applications in high-harmonic generation or in frequency-comb based metrology. Many of todays used mid-IR devices consist of complex, unmovable and cost-intensive setups, having prevented many mid-IR applications from being widely used. A low-loss and flexible WG solution, which does not exists for this spectral domain at the moment, would have immense impact in various fields. Within this proposed project entitled - nanowires in fibers: a base for mid-IR all-solid cladding hollow core fibers - two novel types of mid-IR hollow core fibers with unique cladding structures are to be explored. These all-solid cladding fibers are either based on indefinite metamaterials or on the photonic band gap effect. Both structures will be composed of all-solid claddings surrounding empty cores, making this kind of fiber design unique. This investigation will lead to new physical effects and will pave the way for novel mid-IR devices in a spectral domain beyond that of regular silica fibers. The research output of this proposal is of interdisciplinary origin and will have impact in various areas such as biophotonics, ultrafast optics, spectroscopy and gas lasers.