Measurement And Research On Vibration Amplitude Based On Self-mixing Interference Effect In Semiconductor Laser

When a portion of light emitted from a laser diode source is reflected or scattered back into the laser cavity by an external target, the reflected light, carrying some information of the external target, will mix with the light inside the cavity, causing a modulation of the laser output power, which is monitored by photodiode inside LD or outside. This phenomenon is called as self-mixing effect.The self-mixing effect comes from the optical feedback effect. In recent years, with the development of semiconductor laser technique, making use of self-mixing interference in laser diode actively to measure some physical quantities has become the most potential measurement technique.Firstly, this thesis looked back to the whole process of self-mixing interference, from discovery to its applications. The study purport and applying foreground of self-mixing interference were analyzed.Secondly, the theory of modified Lang-Kobayashi rate equations and theoretical model of a three-mirror F-P cavity were studied; an entirely identical general model of self-mixing interference was got. The influences of system factors on the self-mixing interference signal were discussed.Thirdly, the general self-mixing interference system was set up. The self-mixing interference effects were observed in experiments. The results showed that the vibration amplitude which responses to the slaving voltage exhibits good linearity in corresponding range.Finally, we modified the general self-mixing interference system. Examined by the experiments, the measurement and accuracy are improved greatly. Its significant advantages indicate widely prospective application.