Surface Plasmon Amplification in Transition Metal Nitrides based Gain Assisted Core-Shell Nanoparticles

Transition Metal Nitrides (TMNs) such as ZrN, and TiN has emerged as alternative plasmonic materials to the conventional coinage materials like Au, Ag, Al and Cu etc. The present work assesses the suitability of conventional core-shell nanoparticle for lasing action in SPASER (Surface Plasmon Amplification by Stimulated Emission of Radiation) application. Surface plasmon (SP) amplification is caused by incorporating critical optical gain (g) in the nanoshell core, which leads to the amplification characteristics with lower threshold value for lasing action/process. We report that, the critical optical gain requirement in ZrN is comparable to Au based core-shell nanopartcle. The properties of SPASER and switch able nano scatterer are analyzed using quasistatic approximation (valid for small size particles). By introduction of specific gain in the core medium, the drastic change of scattering efficiency (Qsca) from ultra high to ultra low value and negative absorption cross-section is reported. The feasibility of TMNs as gain assisted surface plasmon amplification properties for various applications like plasmonic laser and nano scatterer is assessed and comparison is made with the most popular plasmonic material, namely Au. Present study can led to the realization of efficient SPASER structures/devices based on TMNs.