ITEE Innovation Expo 2008 : Project Details

Modelling the Self-Mixing Effect in VCSELs

Abstract The effect of temperature and current on the semiconductor laser is an important factor to be considered in laser design and application. A large amount of research and study has been done to look into such area as the demand of the optical communication increase. Theoretically, laser self-mixing occurs when a laser light is scattered by an object into the laser cavity, interferes with the light inside the laser and then coupled into the same laser. By moving or rotating of the object, Doppler Effect occurs and causing the reflected laser light to be shifted. The self-mixing effect creates a large fluctuation of the laser intensity with the Doppler frequency. The objective of this project is to review and conduct an experiment on the self-mixing effect in VCSELs. With the use of vertical cavity surface emitting laser (VCSEL) diode, by varying the laser temperature and the laser current, we observe how the Doppler frequency is being affected. At the same time, compared of the measurement between the change in the temperature and the change in laser current is also discuss. In this thesis, the measurements conducted from the experiment suggest a convenient way to analyze the performance of the VCSELs. Thus, allow us to determine other way to enhance the laser and better design that is suitable for different type of laser application.