Single-fundamental-mode VCSELs have been attractive research subject due to their potential applications such as data transmission in optical network, optical storage and so on. However, single-transverse-mode operation of VCSELs over an entire operating-current range is difficult to achieve due to spatial hole burning and thermal lensing. In this dissertation, we report the single-fundamental-mode operation of "photoniccrystal VCSELs" (PC-VCSELs). The PC-VCSELs are similar to standard VCSELs except that they have photonic crystal defined by air holes in the top mirror region. The two-dimensional triangular-lattice photonic crystal structure has a single defect. By introducing the single-defect photonic crystal to the VCSEL, a waveguide is expected to be formed around the central defect region where the effective index is larger than the surrounding region. We apply the "effective index model" to the PC-VCSEL to understand the guiding structure of the PC-VCSEL. For efficient current injection, oxide or implant aperture is used. The PC-VCSELs show single fundamental mode through the entire current range with side mode suppression ratio over 35dB. Besides, the PC-VCSELs of asymmetric air holes result in polarization pinning. In this work, the modes of the PC-VCSEL are calculated using 3-dimmensional finite-difference time-domain method. Using the simulation results the polarization pinning is explained. This dissertation contains all of the aspects of the design, processing and experimental results of the PC-VCSEL.