Resonant Polymeric Waveguide Cantilever Integrated for Optical Scanning

Abstract

We present SU-8 as an optical waveguide and its integration into a functional one- and two-dimensional (1-D and 2-D) scanning device. The waveguide is fabricated as a tapered structure and cantilever beam (100times85times2100 mum). It is mounted onto a 2-D coupled bimorph piezoelectric actuator and driven at resonant frequencies of 4.71 kHz in the vertical and 25 Hz in the horizontal. This raster motion allows for 2-D image scanning when in combination with a light source and detector. An analysis of the polymer's optical capabilities has shown mode coupling efficiencies of 96% and measured a total power output intensity of 20% with a 633-nm light source. The output power can be attributed to the butt-end coupling misalignment, scattering losses due to surface roughness, and absorption. The total vertical tip displacement is 669 mum with an angle of 25 deg when driven with a 47-mum base excitation. A specific application for the design is in the area of endoscopy, where there is a need for a minimally invasive device that reduces the discomfort experienced by the patient. SU-8 as the functional waveguide is the initial phase in creating a microfabricated endoscope system