An optical waveguide cantilever sensor is introduced, which is determined by monitoring the coupling efficiency between a waveguide cantilever and a waveguide receptor through the cantilever bending. A straightforward model is developed for an optical waveguide cantilever sensor, in which the coupling efficiency between the cantilever and receptor is calculated using the overlap integral. An effective index is introduced to analyze the thickness of input/output waveguides and cantilever for a maximum coupling with a fiber keeping the single-mode operation. The relationship of the optical waveguide sensor (cantilever, gap, and output waveguide) and the sensitivity is presented. As a consequence, we take an optical waveguide cantilever sensor structure of
as an example, and an optimized design is reported. Moreover, the analysis model is compared with a finite-difference beam propagation method. The result means that our model has a similar accuracy but is more simple, intuitive, and time-saving.