Surface plasmon (SP) includes the electromagnetic field distribution of skin depth inside the metal and the evanescent or near-field distribution inside the dielectric or semiconductor. An SP can interact with nearby light emitter through its evanescent or near-field coverage for enhancing emission. From a viewpoint analogous to amplified spontaneous emission, the interaction or coupling between an SP and a light emitter (radiating dipole) can be regarded as a process of amplifying the evanescent or near field of the SP by a gain medium, which includes the radiating dipole. In other words, the radiating dipole transfers energy into the SP for emission, similar to the mechanism of stimulated emission. Therefore, SP coupling with a light emitter can effectively create an alternative emission channel, i.e., SP radiation. This process becomes practically useful in a light-emitting device of relatively poorer crystal quality in its active region. Although metal dissipation can cause SP loss, as long as this energy loss is smaller than that due to the non-radiative recombination process in the active region, emission enhancement of the device can be expected. In other words, SP coupling is particularly useful for increasing emission efficiency of a light-emitting device of inherently low internal quantum efficiency.

报告人简介:楊志忠教授係臺灣大學光電所特聘教授，發表SCI期刊論文近250篇，於國際會議上應邀報告近百次，為OSA及SPIE之fellows。研究領域包括plasmonics, bio-photonics, nano-photonics, MOCVD and MBE growths of GaN and ZnO related nanostructures.