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.