Direct milling and casting of polymer-based optical waveguides for improved transparency in the visible range

• Published in: Journal of micromechanics and microengineering 2006-02, Vol.16 (2), p.375-381
• Main Authors: Snakenborg, D, Perozziello, G, Klank, H, Geschke, O, Kutter, J P
• Format: Article
• Language: English
• Subjects: Applied fluid mechanics; Applied sciences; Electronics; Exact sciences and technology; Fluid dynamics; Fluidics; Fundamental areas of phenomenology (including applications); Instruments, apparatus, components and techniques common to several branches of physics and astronomy; Mechanical engineering. Machine design; Mechanical instruments, equipment and techniques; Microelectronic fabrication (materials and surfaces technology); Micromechanical devices and systems; Physics; Precision engineering, watch making; Semiconductor electronics. Microelectronics. Optoelectronics. Solid state devices
• ISSN: 0960-1317; 1361-6439
• DOI: 10.1088/0960-1317/16/2/023

Polymer waveguides fabricated from photoresist have an inherent high propagation loss in the short visible wavelength range caused by absorption due to the added photosensitizers. We have addressed this problem by development of two novel methods for the fabrication of microfluidic systems with integrated optical waveguides. Polymethylmethacrylate (PMMA) is dissolved in anisole and 'doped' with styrene-arcylonitrile copolymer to vary the refractive index. The doped PMMA with a higher refractive index is then spin coated onto a PMMA substrate with a lower refractive index to provide waveguide properties. Direct micromilling enabled us to fabricate 100 mum wide optical waveguides. Propagation losses of less than 1 dB cm-1 could be achieved throughout the entire visual range down to a wavelength of 400 nm. A casting process amenable to high number production of such devices was furthermore developed.