Dengxin Ji

Efficient end-fire coupling of surface plasmons on flat metal surfaces for improved plasmonic Mach-Zehnder interferometer

An efficient on-chip coupling mechanism is essential for nanoplasmonic circuits and elements. We show theoretically that end-fire coupling is a promising candidate to deliver light into regions with subwavelength dimension on flat metal surfaces. A design and optimization principle is presented for a flat metal surface and further demonstrated in a plasmonic Mach-Zehnder interferometer platform. The physical mechanism is discussed based on reciprocity. By considering the radiation pattern and position of the incidence, the coupling efficiency at the metal/air interface can be enhanced up to 77.6%–95.4%, which is promising to develop energy-efficient applications for on-chip plasmonic waveguide networks and sensors.

A metal-insulator-metal plasmonic Mach-Zehnder interferometer array for multiplexed sensing

A multi-layered metal-insulator-metal plasmonic Mach-Zehnder interferometer (MZI) is proposed to work as an array for multiplexed sensing. The interference patterns based on wavelength modulation and intensity modulation are modeled analytically and numerically, showing a high figure of merit over 170 for intensity-interrogated sensing. The proposed structure can overcome the one-slit illumination limitation of previously reported single-layered double-slit plasmonic MZI and will enable portable, high-throughput and sensitive biosensing applications.

Surface dispersion engineering of Ag–Au alloy films

By controlling the content ratio of Ag and Au during the metal co-sputtering process, we demonstrate that the surface dispersion properties of alloy metal films can be manipulated with no need to tune the geometric parameters for surface patterns. This inexpensive technology provides a different way to engineer the surface dispersion properties of plasmonic metamaterial components on a chip.

On-chip plasmonic interferometer array for portable multiplexed biosensing system

We report a multiplexed intensity-modulated sensing platform using a plasmonic interferometer array with the resolution of 1.6×10-5 RIU. This sensing mechanism is then integrated with a smartphone imaging system to demonstrate a portable biosensing device.