Photonic-Crystal Surface-Emitting Lasers: Review and Introduction of Modulated-Photonic Crystals

Photonic-crystal surface-emitting lasers (PCSELs) have attracted much attention for their unrivaled capabilities, such as broad area, coherent resonance, tailored beam patterns, and beam steering. In this paper, we first review the progress of PCSELs, then introduce a novel concept of modulated photonic-crystal surface-emitting lasers (M-PCSELs) for realizing both lasing oscillation and on demand, beam diffraction for any two-dimensional direction in free space without the need for external elements. This unique concept paves the way toward the development of semiconductor lasers with completely controllable beams.