Polarization-Controllable Plasmonic Enhancement on the Optical Response of Two-Dimensional GaSe Layers.

Resonant plasmonic coupling has been considered as a promising strategy to enhance the optical response and manipulate the polarization of two-dimensional (2D) layer materials toward the practical applications. Here, a hybrid structure with periodic Ag nanoprism arrays was designed and fabricated on 2D GaSe layers to enhance these optical properties. By using the optimized hybrid structure with well-matched resonance, significant enhanced Raman scattering and band edge emission were successfully realized, and it is also interestingly found that the higher enhancement would be achieved while decreasing the thickness of GaSe layers. Theoretical simulation indicated that the strongly enhanced local field and the modified charge densities are the main reasons. By further introducing the patterned gratings on the plasmonic hybrid structure, selective excitation with controllable polarization was readily realized, besides the strongly enhanced photoluminescence intensity. This work provides a strategy for the plasmonic engineering of polarization controllable 2D optoelectronic devices.