In this paper, four different types of miniaturized Microelectromechanical Systems (MEMS) based tunable lasers, from
photonic MEMS laser designs to fabrication techniques, are introduced. These tunable lasers are MEMS external cavity
laser, injection-locked laser, coupled-cavity laser, and dual-wavelength laser. The properties, functionalities and
performances of the MEMS-based tunable lasers are individually discussed based on their experimental results. The
potential applications in fiber optical communications are also identified. These tunable lasers, which are more
innovative in terms of design, specifications and configurations compared to traditional lasers, also provide significant
improvements in their functionalities.