Micromechanical Behavior and Optical Characteristics of a Free-Standing Polymer Waveguide

This paper presents an experimental characterization of the microoptomechanical behavior of a mechanically deflected free-standing polymer waveguide. We evaluate the total optical loss of the mechanically deflected waveguide, considering propagation loss, input/output coupling loss and mechanical bending loss. For the experimental evaluation of the total optical loss, we design and fabricate three different sets of waveguide structures: the straight waveguides for propagation and coupling loss measurement; the curved waveguides for curvature loss measurement; the suspended waveguides for mechanical bending loss measurement. From the straight waveguides, we have measured the propagation loss of 5.4±1.1dB/cm and the coupling loss of 5.3±2.4dB, respectively. We have measured the curvature loss of ±4dB/rad for the curved waveguides having the radius of curvature in the range of 200–2,000μm. From the waveguide bending test, we have measured the elastic limit and the failure strength of the polymer waveguide as 5±1MPa and 23±8MPa, respectively. We also find that the mechanical bending loss is rapidly increased to 12–25dB for the waveguide deflection beyond the elastic region. The rapid increase of the mechanical bending loss in the large deflection region is due to the abrupt change of propagation angles as well as the mechanical defect generated in the waveguides.