Ultrashortpuls laser system for coupling to a near-field optical microscope

对于我们在纳米光子学领域的研究，特别是对近红外和中红外光谱区域的研究，我们需要一种灵活的、可广泛调谐的时间分辨率为数百飞秒的激光光源。我们将把这个光源耦合到一个已经存在的散射型近场光学显微镜上，以便研究从可见光到大约15微米波长的广泛光谱范围的光子表面波。这项研究的一个特别重点将放在极化子上，它是通过红外辐射与纳米结构介质衬底中声子的振荡耦合而建立的。其他研究领域包括表面增强分子光谱和由红外活性等离子体材料(如氮化锆和氮化钛)激发的热电子引起的化学能转换。通过将激光耦合到近场光学显微镜，我们将能够进行空间分辨率仅为几纳米的实验。这将使红外辐射在远低于衍射极限的微小区域内局部化的基础研究工作成为可能，并在分子光谱学、成像和能量转换方面得到应用。优选的系统提供了额外的可能性，例如泵浦/探测超短脉冲光谱和从720 nm到16微米波长的非常高的可调谐范围。

For our research in the area of nanophotonics, particularly for studies in the spectral regime of the near- and mid-infrared, we are in need of a flexible and widely tunable laser source with a time resolution of hundreds of femtoseconds. We will couple this light source to an already existing scattering-type near-field optical microscope, in order to study photonic surface waves over a wide spectral regime, from the visible to wavelengths of about 15 microns. A particular focus of this research will lie on polaritons, set up via the coupling of infrared radiation to the oscillations of phonons in nanostructured dielectric substrates. Additional areas of study are surface-enhanced molecular spectroscopies and chemical energy conversion caused by hot electrons excited in infrared-active plasmonic materials such as ZrN and TiN. Via coupling of the laser beam to the near-field optical microscope, we will be able to perform experiments with a spatial resolution of only a few nanometres. This will enable fundamental research work on the localization of infrared radiation into minute areas far below the diffraction limit, with applications in molecular spectrosocpy, imaging, and energy conversion. The preferred system offers additional possibilities such as pump/probe ultrashort pulse spectroscopy and a very high tunability range from 720 nm to 16 microns wavelength.