Effect of incident laser power and incorporating polariton effects in GaN microrods

Abstract Optical property of GaN microrods was investigated by power dependent photoluminescence (PL). Two PL peak envelops were observed in near band edge region and this feature has been attributed to the exciton-photon coupling. Clear mode formation in PL spectrum was observed and modes were redshifted slightly with the increase in laser power for two microrods. Redshifting of PL peak envelops in near band edge region was huge in one microrod as compare to other microrods with the increase in laser power. This is attributed to both the electron-hole plasma effect and exciton-photon coupling which depends on the morphology. Modes in the defect related region were prominent than the modes in near band edge region at low laser power and with the increase in laser power, modes in the defect region disappears and modes in the near band edge region becomes more prominent. Cavity modes get guided in the cavity at higher power when the polariton formation takes place. Cavity modes are not guided at low power when modes are photonic.