Fiber-Optic Directional Coupler as Micro-Displacement Sensors
Samian1) and Herri Trilaksana2)
1) ,2) Department of Physics, Faculty of Science and Technology,
Airlangga University, Surabaya 60115, Indonesia.
herrifisika@gmail.com
Experiment of directional coupler multimode plastic optical fiber as micro-displacement had been done based on simple technique of intensity modulation. The directional coupler that had been made by hand has a coupling ratio 0.37. It was made by fused method with optical fiber polishing process. The experiment detected micro displacement of object (front silvered mirror) around 5 mm in order. He-Ne Laser (632,8 nm) 1mW in power is a light source and OPT 101 detector (Burr Brown) detected optical power losses caused by displacement of object. Theoretical analyses of optical sensor performance with the light source as Gaussian approximation showed a good result. Sensor characterization showed the range of measurement in 3.6 mm with 1.1 mm as a linear range response and high sensitivity namely 25.5 mW/mm. Simple in design and good performance are the main factor to apply this directional coupler in industrial application, such as a micro displacement sensor or another physical parameter based on the displacement mechanism.
Keyword : directional coupler, multimode optical fiber, displacement sensor