Advances in fabrication technologies have allowed the fabrication of laser cavities with arbitrary 2-D shapes. 2-D cavities have a wide variety of spatial modes, which have different wavefunctions. From the viewpoints of both fundamental physics and practical applications, it is important to selectively excite one desired mode from among many spatial modes. In this paper, we review the methods of selective mode excitation for 2-D microcavity laser diodes based on the control of both cavity shape and electrode contact pattern. We also review two major applications of the selective excitation technique to fundamental research in both quantum and laser chaos. One is the observation of chaos-assisted tunneling, and the other is compact chaotic laser devices that consist of a 2-D microcavity laser and an external feedback cavity. Finally we refer to the potential applications of the selective excitation technique to such functional optical devices as beam-switching devices and polarization-switching devices.