Vertical-cavity surface-emitting lasers are promising devices on the semiconductor laser market, and offer numerous advantages over edge-emitters in the low power regime. Physics-based comprehensive modeling allows one to shorten the development period of future products and to reduce the design costs. These devices are sometimes noncircular, either owing to anisotropic oxidation speed or to achieve special characteristics, such as high-power single-mode output. Problems arising with complex structures call for three-dimensional numerical solutions. This book reviews the simulation methods for vertical-cavity surface-emitting lasers and provides novel approaches to investigate their more challenging variants. Electrical, thermal and optical properties are demonstrated on illustrative examples. The analysis helps to get insight into these exciting lasers, and should be especially useful to professionals in telecommunication and modeling fields.