ABSTRACT
This chapter illustrates the fundamental optical properties of surface-emitting lasers incorporating subwave length periodic structures, called photonic crystals. Photonic crystals are periodic structures designed to affect electromagnetic waves in a similar manner to how solid-state crystals affect electrons. The physics of photonic crystals has much in common with solid-state physics, as both concerns the solution of wave equations in a periodic medium. One of the most important properties of photonic crystals is the photonic bandgap, i.e., a range of frequencies in which light cannot propagate through the crystal. Two- and three-dimensional photonic crystals can be considered a multi-dimensional equivalent of distributed Bragg reflectors. Photonic crystals are seldom used in edge-emitting lasers. In vertical-cavity surface-emitting lasers (VCSELs), photonic crystals are used to provide effective light confinement. By etching a regular lattice of holes in either the DBRs or the VCSEL cavity, together with intentional lattice defects, it is possible to mold the optical mode distribution.
