Compact surface emitting laser with photonic crystal-metal hybrid structure

Abstract

A photonic crystal laser has been widely studied in the field of laser cavity owing to its excellent optical properties. However, because increasing free space radiation loss for reducing physical device size, a conventional photonic crystal laser still remains to have large structure. Although, several methods have been suggested, it is still difficult to meet the demands of compact coherent light source-based applications. In this thesis, I suggest metal-photonic crystal hybrid cavity structure combining photonic crystal slab and 2.5D metallic external reflector to obtain compact photonic crystal laser. To find the expected lasing mode, photonic bandstructure was calculated. In-plane and out-of-plane photon confinement effect of metallic external reflector is confirmed through three dimensional finite time difference method. Through separate analysis of optical loss for absorption and radiation, limitation of applicability of proposed structure is verified, and discuss what problem have to be solved for miniaturization. Also, the metal layer effect on temperature which is important for laser performance is analyzed through finite element method. I confirm that thermal effect by pumping process could be suppressed through surrounding metal layer. Various size of proposed hybrid cavity structure are fabricated, and single mode lasing at room temperature of PhC laser with only $5 \mu m$ footprint are observed. Smaller than $5 \mu m$ of hybrid cavity structure cannot achieve lasing owing to the large optical loss. Based on above results, I suggest modified hybrid cavity structure which removes optical loss mechanism, and I confirm that optical loss of $2 \mu m$ of modified structure is better than $5 \mu m$ of previous hybrid cavity structure.