Femtosecond laser processing, microstructuring of transparent polymers for Lab-on-Chip applications

近年来，IQ小组成功地使用了密集的局域飞秒激光照射来证明材料的改性，从而在聚合物基片和薄膜的内部局部增加了折射率，并将这项技术确立为一种可重复性和可靠性的方法。可以得到单模衰减值在0.5dB/cm以下的不同类型的光波导。因此，所有以前的文学价值都被削弱了近一个数量级。新项目的重点是飞秒波导的实际应用，以及在考虑到该工艺的全3D能力的情况下实现新型复合波导结构。在写入过程中，通过稳定光束位置来进一步降低传输散射损耗，并在写入光束中使用横向相位调制器(SLM)来实现软件控制的焦点整形。这使得飞秒激光能够同时写入几个相邻且相互关联的焦点。通过在写入过程中改变SLM的相位掩模，可以一次实现复杂的2D和3D耦合器结构。基于经过处理的聚合物薄膜，透明地放置在智能手机/平板电脑的显示屏上，这是迈向“移动实验室”的第一步。在胶片中运行的波导网从显示器以多种颜色单独馈送，并将光传输到前置相机，在那里可以灵敏地检测到光并进行颜色解析。通过这种方式，可以灵活地读取分布在胶片上的传感器。最后，利用相同的飞秒激光写入装置，可以将空心毛细管作为微流控通道写入聚合物衬底。与光波导相结合，在单个生产步骤中就可以创建一个单独的集成芯片上实验室。

In recent years, the IQ group has succeeded in using intensive localized femtosecond laser irradiation to demonstrate material modifications and thereby local refractive index increases in the interior of polymer substrates and films and to establish this technique as a reproducible and reliable method. Waveguides of different types with single mode attenuation values below 0.5 dB/cm could be demonstrated. Thus, all previous literature values have been undercut by almost one order of magnitude. The new project focuses on the practical use of femtosecond waveguides and the realization of novel complex waveguide structures under consideration of the full 3D capability of the process. The propagation scattering losses are to be further reduced by beam position stabilization during writing, and software-controlled focus shaping is to be realized by using a transverse phase modulator (SLM) in the writing beam. This enables simultaneous femtosecond laser writing with several adjacent and interrelated foci. By changing the phase mask at the SLM during the writing process, complex 2D and 3D coupler structures can be realized in one go. The first steps towards a 'mobile lab' based on a processed polymer film, which is transparently placed over the display of a smartphone/tablet, are the result. A network of waveguides running in the film is fed individually in multiple colors from the display and transports the light to the front camera, where it is detected sensitively and color resolved. In this way, sensors distributed over the film can be read flexibly. Finally, hollow capillaries can be written in polymer substrates as microfluidic channels with the same femtosecond laser writing setup. Combined with the optical waveguides, an individual integrated lab-on-a-chip is created in a single production step.