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° 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° to 180°, the measured divergence angles are less than 4.8°. 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.