In this paper, the feasibility of a new vehicle axle detector for roadways based on fiber optic Mach-Zehnder interferometer was evaluated. This new vehicle axle detector used in this study has a relatively simple sensing principle. Thus the system can be composed of inexpensive and reliable components for the application to transportation system compared with the traditional vehicle axle detectors. The configuration and performance of the new vehicle axle detector was described. The process of conversion of the detected interferometer sensor signal into the weight of a vehicle axle was proposed. Simulating results show that the sensing response of the embedded fiber optic vehicle axle detector based on Mach-Zehnder interferometer can meet the requirements of a vehicle axle detector. In addition, a high-speed signal processing system was designed for the interferometer. The new vehicle axle detector has good potential as a basic sensor unit which can be widely used in ITS to detect the vehicle axle weight and identify the type of a vessel which passes over the detector.
In this paper, the principle of a cantilever-beam micro-mechanical switch with SiO2 optical waveguide on silicon is described, and the solid model of the switch is established and finite element method (FEM) is used in studying its dynamic characteristics. Under different parameters, the modal characteristics are simulated and analyzed. The influence of the switch structural dimension on the resonant frequency and dynamic characteristics of the switch are investigated, and the harmonic response of the micro-mechanical optical switch is achieved. The results of analysis offers reliable basis for the structure design of the micro-machined cantilever optical switch.