Phase-shift effect on a two-dimensional surface-emitting photonic-crystal laser

Theoretical analysis was performed by means of the finite-difference time-domain method to examine the mode properties of two-dimensional surface-emitting photonic-crystal lasers with elliptical air holes. It was found that a single-lobed beam pattern could be obtained from the device surface by introducing a phase shift to the center of the crystal. The effects of the shift on the polarization mode and on two-dimensional optical coupling (which is needed for single-mode lasing over a large area) were also investigated. It was shown that the phase shift emphasized the linear polarization of the emitted beam due to symmetry reversal. On the other hand, it was also found that the shift did not spoil the two-dimensional optical coupling.