Optomechanical characterization of mechanically deflected free-standing polymer waveguides

Abstract

We characterize the micro-optomechanical properties and behavior of mechanically deflected free-standing polymer waveguides. The total optical loss of the mechanically deflected waveguides is evaluated, including propagation loss, input/output coupling loss, geometric curvature loss and mechanical bending loss. Three different sets of polymer waveguides are designed, fabricated and tested: straight waveguides for propagation and coupling loss measurement; curved waveguides for curvature loss measurement; freestanding waveguides for mechanical bending loss measurement. From the straight and curved waveguides, the propagation loss has been measured as 5.4 +/- 1.1 dB/cm with the coupling loss of 5.3 +/- 2.4 dB, and curvature loss as 4 dB/rad in maximum value, respectively. The mechanical bending loss, measured by the waveguide bending test, rapidly increased to the range of 12-25 dB for the waveguide deflection beyond the elastic region. The reason for the rapid increase of the mechanical bending loss in the large deflection region can be explained as being due to the abrupt change of propagation angles as well as the mechanical defect generated in the waveguides. Furthermore, the elastic limit of the polymer waveguide has been observed at 5 +/- 1 MPa, and the failure strength has been measured as 23 +/- 8 MPa from the waveguide bending test.