Compact surface plasmon amplifier in nonlinear hybrid waveguide

Surface plasmon polariton（SPP）, a sub-wavelength surface wave promising for photonic integration, always suffers from the large metallic loss that seriously restricts its practical application. Here, we propose a compact SPP amplifier based on a nonlinear hybrid waveguide（a combination of silver, LiNbO3, and SiO2）, where a couple of Bragg gratings are introduced in the waveguide to construct a cavity. This special waveguide is demonstrated to support a highly localized SPP-like hybrid mode and a low loss waveguide-like hybrid mode. To provide a large nonlinear gain, a pumping wave input from the LiNbO3 waveguide is designed to resonate inside the cavity and satisfy the cavity phase matching to fulfill the optical parametric amplification（OPA） of the SPP signal. Proper periods of gratings and the cavity length are chosen to satisfy the impedance matching condition to ensure the high input efficiency of the pump wave from the outside into the cavity. In theoretical calculations, this device demonstrates a high performance in a very compact scheme（~3.32 μm） and a much lower pumping power for OPA compared with single-pass pumping. To obtain a comprehensive insight into this cavity OPA, the influences of the pumping power, cavity length, and the initial phase are discussed in detail.

Manipulation of plasmonic wavefront and light–matter interaction in metallic nanostructures: A brief review

The control and application of surface plasmons （SPs）, is introduced with particular emphasis on the manipulation of the plasmonic wavefront and light-matter interaction in metallic nanostructures. We introduce a direct design methodology called the surface wave holography method and show that it can be readily employed for wave-front shaping of near-infrared light through a subwavelength hole, it can also be used for designing holographic plasmonic lenses for SPs with complex wavefronts in the visible band. We also discuss several issues of light-matter interaction in plasmonic nanostructures. We show theoretically that amplification of SPs can be achieved in metal nanoparticles incorporated with gain media, leading to a giant reduction of surface plasmon resonance linewidth and enhancement of local electric field intensity. We present an all-analytical semiclassical theory to evaluate spaser performance in a plasmonic nanocavity incorporated with gain media described by the four-level atomic model. We experimentally demonstrate amplified spontaneous emission of SP polaritons and their amplification at the interface between a silver film and a polymer film doped with dye molecules. We discuss various aspects of microscopic and macroscopic manipulation of fluorescent radiation from gold nanorod hybrid structures in a system of either a single nanoparticle or an aligned group of nanoparticles. The findings reported and reviewed here could help others explore various approaches and schemes to manipulate plasmonic wavefront and light-matter interaction in metallic nanostructures for potential applications, such as optical displays, information integration, and energy harvesting technologies.

On-chip silicon light source： from photonics to plasmonics

Practical silicon photonic interconnects become possible nowadays after the realization of the practical silicon light sources, where the hybrid integrations of III-V semiconductors and silicon by bonding play a fundamental role. Photonic interconnects dissipate substantially less power and offer a significantly greater information bandwidth than those of electronic interconnects; however, one emerging problem is the size mismatch between photonic and electronic components when integrated on a chip. Therefore, surface plasmonic source with deeply sub-wavelength size is under intense investigation as the next generation Si-based light source for on-chip interconnects. In this paper, we shall review some of the latest achievements on this topic.