Light-matter interactions can be hugely enhanced in plasmonic nanostructures by strong confinement of electromagnetic fields, which has incited many efforts to develop ultra-compact nonlinear devices among other types of nanoplasmonic devices. Previous work has focused upon wave mixing and modulation at quite low efficiencies. In this study, we reveal bistable switching in plasmonic antennas with a monolayer graphene or MoS2 sheet in their sub-nanometer hotspot junctions. The bistability derives from the interplay between a highly efficient wave mixing interaction and a strong positive feedback by the Purcell effect. We build a theoretical model that well reproduces the experiment results. The discovery of bistable plasmonic nano-switches is key to understanding and making efficient nonlinear plasmonic devices.
Surface plasmon resonance (SPR) devices have been widely used in label-free biosensing applications due to their convenient surface wave configuration and the capability to optically detect biomolecule surface binding with a high stability and uniformity between different experiments. Meanwhile, integrating SPR nanostructures onto single-mode fiber (SMF) end facets provides unique advantages such as flexible geometry, compact sizes and in vivo monitoring capability. To improve the performance of SMF end facet SPR devices which are usually limited by guided mode diffraction, following our previous work on plasmonic crystal cavities , in this work we demonstrate a plasmonic distributed feedback (DFB) cavity with a phase shift section. The DFB structure contains a periodic array of nanoslits in a gold film, which provides a surface plasmon polariton (SPP) bandgap from 865 to 877 nm on the water-gold interface. A phase shift section is embedded at the center of the DFB structure to introduce an SPR defect state within the SPP bandgap. The devices were fabricated onto the fiber end facets by a glue-and-strip transfer process . To demonstrate real biosensing implementations, the reflection spectra of the SMF guided lightwaves were taken in real-time to detect refractive index change, adsorption of bovine serum albumin onto gold surface, and the association and dissociation between human immunoglobulin G (hIgG) and its antibody.
 X. He, H. Yi, J. Long, X. Zhou, J. Yang and T. Yang, "Plasmonic Crystal Cavity on Single-Mode Optical Fiber End Facet for Label-Free Biosensing," Applied Physics Letters 108, 231105 (2016)
Conference Committee Involvement (1)
Photonic Microdevices/Microstructures for Sensing IV
26 April 2012 | Baltimore, Maryland, United States