Technologies on Display

D2 - Photonic Sensors based on Surface Plasmon Resonance Effect

Surface plasmon resonance (SPR) is an intriguing effect associated with interaction between EM wave and metal surface. When an optical beam hits a metal-dielectric interface at a specific angle, some of the optical energy will be transferred. It forces the free electrons to move along with the incident optical wave. ¡§Surface Plasmons¡¨ thus refer to such oscillations of free electrons in the metal film.

The existence of SPR in metal film (typically gold) makes it ideal for detecting material variations within a thin region close to the film surface. This project aims to exploit the special properties of SPR for sensor applications. At CUHK we focus on detecting the optical phase. This novel approach has been shown to be at least one order of magnitude more accurate than conventional methods. To further increase instrument stability we have also developed a differential technique to remove unwanted drifts caused by environmental disturbance.


  • Medical care
  • Consumer health products
  • Chemical industry
  • Pharmaceutical/drugs
  • Environmental/pollution monitoring
  • Semiconductor/wafer fabrication


  • High sensitivity (up to 4 x 10-8 refractive index unit)
  • Excellent stability from differential measurement
  • Biomolecules such as antibody, DNA and protein can be detected
  • Capable of measuring reaction rate
  • Label-free sensing and real-time measurement

Principal Investigator
Prof. Aaron Ho
Department of Electronic Engineering