This paper reports on an improved optical waveguide microcantilever sensor with high sensitivity. To improve the sensitivity, a buffer was introduced into the connection of the input waveguide and optical waveguide cantilever by extending the input waveguide to reduce the coupling loss of the junction. The buffer-associated optical losses were examined for different cantilever thicknesses. The optimum length of the buffer was found to be 0.97 μm for a cantilever thickness of 300 nm. With this configuration, the optical loss was reduced to about 40%, and the maximum sensitivity was more than twice that of the conventional structure.

An analysis model for an optical waveguide microcantilever sensor is developed combining the optical and mechanical models. An improved optical waveguide microcantilever sensor with a buffer is provided and taken as an example to explore using the analysis model. A systematic and detailed discussion about the couplers for the input waveguide to optical waveguide cantilever and the optical waveguide cantilever to the output waveguide of the improved waveguide cantilever sensor is presented. The sensitivity of an improved optical waveguide cantilever sensor is evaluated by analyzing the input/output waveguide, buffer, microcantilever, and gap. An improved optical waveguide microcantilever sensor by adding a buffer shows a sensitivity of 5.7 × 10 −4 nm −1 , which is improved by 51.3%, compared with a conventional optical waveguide microcantilever sensor. The design of an optical waveguide cantilever sensor is a trade-off of different design parameters. These will be helpful for the study of an optical waveguide cantilever sensor.

This paper introduces a planarisation SiO 2 layer into the configuration of ZnO-silicon-on-insulator for constructing an acoustical resonant cavity to enhance the acoustic density on a silicon-on-insulator waveguide. The improved configuration with a planarisation SiO 2 layer can increase the acousto-optical interaction by about three times and 20% compared with acousto-optical configuration of ZnO pads only in an interdigital transducer region and all over a silicon on insulator. Moreover, an introduction of a planarisation SiO 2 layer can reduce acoustic reflection on optical waveguide and optical waveguide loss for an acousto-optical device on silicon-on-insulator optical waveguides.