Lateral Cavity Photonic Crystal Surface Emitting Laser With Narrow Divergence Angle

We demonstrate an electrical injection lateral cavity photonic crystal surface emitting laser (LC-PCSEL) with a narrow divergence angle of less than 4.8 degrees and nearly circular beam at communication wavelength. Different etching depth of PC air hole results in varied divergence angle for both PC element and PC array structure. Shallow-etching PC array structure has a great advantage in achieving a narrow divergence angle, nearly circular beam, high far-field intensity, and large fabrication tolerance. By rotating the device from 0 degrees to 180 degrees, the measured divergence angles are less than 4.8 degrees. Therefore, a narrow divergence angle LC-PCSEL with circular beam is achieved due to six-fold rotational symmetry. This is a demonstration of the 2-D coherent oscillations, which reflects the nature of 2-D PC. Our demonstration promises to realize extensive applications in on-chip communication, and interconnects for surface emitting laser in communication wavelength.