In this paper the mechanism of reflective fiber-optic vibration sensor has been researched by mathematical modeling and Simulation. Research shows that fiber structure, the numerical aperture and core diameter of fiber, can affect the performance of RIM-FOS. With the increase of the numerical aperture, the peak point and range of detection move forward, received power is not changed, sensitivity is improved; with the increase of core diameter of transmitting fiber, power peak and sensitivity decreases; along with the core diameter of receiving fiber increases, the peak power increases, the slope before sensitivity increased. According to the research results, the best SNR is obtained in an experimental system that the 62.5μm of transmitting fiber and 100μm core diameter of receiving fiber is adopted.
In this paper the mechanism of BBO crystal component for frequency resolved optical gating technique has been researched by mathematical modeling and Simulation. Research shows that thickness of the crystal and the phase matching angle are important parameters affecting the measurement performance. Crystal thickness determines the pulse width limit which this crystal can distinguish; when the phase condition is matched between the fundamental frequency and second-harmonic of light, the SHG efficiency of incident light is highest. According to the calculations, An BBO crystals with 3.5mm thickness, 20.56 degrees phase matching angle is adopted to realize the crystal component for tens to hundreds of femtoseconds pulse width measurement.