Planar Photonic Crystal Vertical-Cavity Surface-Emitting Lasers

Planar index-guided proton-implanted photonic crystal vertical-cavity surface-emitting lasers are fabricated and characterized. Index guiding from the photonic crystal improves the performance of the lasers by creating a stable light output versus current response, reducing the threshold current, and enhancing the differential quantum efficiency. Examination of the etch depth dependence of laser efficiency reveals various mechanisms that affect the laser performance and modal properties such as optical loss, Joule heating, and spectral gain-resonance alignment. Photonic crystal designs can be chosen which result in lasing operation only in the fundamental transverse mode from threshold to maximum power, even for the condition of blue-shifted gain spectrum relative to the cavity resonance. Suitable photonic crystal designs are shown to be manufacturable due to the planar device topology, the use of optical lithography in all processing steps, and compatibility with virtually any vertical-cavity surface-emitting laser epitaxial designs.