Vibration and Acceleration Sensor Using the Optical Fiber with Bulb-End

Abstract

Vibration-sensor made of an optical fiber with bulb-end (this also acts as a seismic mass) in V-groove on an Si substrate is proposed, and fundamental characteristics of this sensor are demonstrated. Nearly flat frequency dependence of the optical output was obtained in the frequency range between observed 40 and 1200Hz under the constant acceleration. Resolution (or equivalent noise level) of 0.3m/s² is attained in this prototype device. Vibrations with many modes in a vibrator are analyzed by FFT analysis of optical signals output from this vibration-sensor. Setting displacement of optical axes, about 30μm, between optical fiber with bulb-end (input fiber) and output fiber, and small amplitude of about 1μm of the input fiber lead to linear relationship between acceleration and optical output.