Plasmon-enhanced Two-dimensional Material Photonic Devices With Ultra-smooth Metallic Films

Surface plasmons can confine light in the subwavelength scale and achieve local field enhancement,thus effectively enhance light-matter interactions.Two-dimensional（2D）materials have a variety of novel opto-electronic properties.However,the interactions between light and 2D materials,due to their atomic thickness,are generally week,which hinders the performance of 2D opto-electronic devices.Recently,plasmonics enhanced 2D material photonic devices is becoming the focus of interest.The combination of plasmonic structures with 2D materials can enhance the absorption,surface Raman signals as well as the nonlinear effects of 2D materials.However,the inherent absorption and scattering losses of metals severely affects the performance of plasmonic devices.Therefore,in order to better improve the performance of photonic devices made of 2D materials,it is necessary to reduce the losses of the metal films.This thesis explores the low loss properties of ultra-smooth metallic films for plasmonics enhanced two-dimensional material photonic devices.The main work includes:（1）We proposed a plasmonic cavity with a Mo Se₂ film as the gain medium.We studied its optical properties with numerical simulations and analyzed its possibility for light amplification.The simulation results show that the optical absorption loss of metals plays an important role in the properties of the plasmonic cavity.If we used a normal loss gold to build the plasmonic resonant cavity,the whole structure was absorptive.If we reduced the metal loss to 1/4 of the normal metal,the whole structure changed from absorbing light to emitting light,realizing light amplification.（2）We fabricated ultra-smooth,low-loss metal films by template peeling.Atomic Force Microscopy（AFM）results show that metal films prepared by template peeling have a better three-dimensional morphology than those obtained by direct vapour deposition,while the relative dielectric constant of the metal films obtained by template peeling is lower in the imaginary part at the 400-800 nm band as measured by ellipsometry.This makes it possible to realize the high performance 2D material plasmonic devices.（3）We combined the ultra-smooth metal film with the metallic nanodisk array and explored the fabrication of Mo Se₂ integrated plasmonic resonant cavities.The fabricated plamsonic resonant cavity has a resonant linewidth of about 60 nm and its quality（Q）factor exceeds 20.Our work may pave the way for novel high Q 2D material plasmonic devices such as plasmonic lasers or spasers.