Project: Enhanced transmission and absorption with plasmonic and metamaterials nanostructures

Photonic technologies may provide necessary solutions for many challenges we are currently facing in health, medicine, energy, information technology, computer, space, safety, security, etc. In particular, energy related issues have become one of the most critical challenges, due to limited energy resources, globe climate changes, and exponentially increased energy consumption demands.

‘Green photonics’ is one of the key technologies that has the potential to reduce the energy consumption and improve the global balance of atmospheric carbon dioxide. Green Photonics comprises photonics solutions that generate or conserve energy, cut greenhouse gas emissions, reduce pollution, yield environmentally sustainable outputs or improve public health. Green photonics covers a broad range of optical technologies and applications: photovoltaic energy generation, highly efficient solid-state lighting, advanced sensing and instrumentation for environmental monitoring, new energy-efficient communication technologies and clean manufacturing using laser processing. All the photovoltaics, sensing and solid-state lighting devices need metallic contacts for conducting or harvesting electrons so that the devices can be functional. Metals at optical (visible or infrared) regime are usually opaque but with high reflectivity. Thus, when light illuminates a thin metal (e.g., gold or silver) film, most of light is reflected back and the transmitted light through the film is close to zero. However, if the metal film is nano-structured with holes or particles (i.e., plasmonic and metamaterial nanostructures), it can become transparent or absorbing, with low reflectivity (i.e., enhanced transmission or absorption).

The present project aims to investigate such plasmonic and metamaterial structures, their transmission and absorption properties, and their possible applications in photovoltaic energy generation, highly efficient solid-state lighting, and advanced sensing. The current project stands in the frontline of the plasmonic and metamaterial research, with topics ranging from design and fabrication technologies to practical device applications. With the success of the current project, it should be able to have a great impact on the advance of optical metamaterials, plasmonics, and their practical applications. It could also foster new knowledge and new start-ups, through the planned industrial collaborations on practical component applications.

Metals at optical (visible or infrared) regime are usually opaque but with high reflectivity. Thus, when light illuminates a thin metal (e.g., gold or silver) film, most of light is reflected back and the transmitted light through the film is close to zero. However, if the metal film is nano-structured with subwavelength-size holes or particles (i.e., plasmonic and metamaterial nanostructures), it can become transparent or absorbing, with low reflectivity (i.e., enhanced transmission or absorption). The present project aims to investigate such plasmonic and metamaterial nanostructures, their transmission and absorption properties, and their possible applications in photovoltaic energy generation, highly efficient solid-state lighting, and advanced sensing.

The objectives of the present project include: (1) Development of simulation tools for plasmonic and metamaterial nanostructures; (2) Designs of plasmonic and metamaterial nanostructures for enhanced transmission and absorption; (3) Experimental demonstration of enhanced transmission and absorption structures; and (4) Investigation of plasmonic and metamaterial nanostructures for applications in light emitters, detectors, and solar cells, along with the investigation of the implementation technologies. The research shall have significant impacts on enhance the efficiency of solid-state lighting, sensing, and photovoltaics.