Near infrared surface plasmon resonance sensing on a silicon platform.

摘要

The thesis describes the development of novel sensing configurations, based on Surface Plasmon Resonance (SPR) transduction, which could be used for investigation of optical and physical properties of thin films and for the development of the bio- and chemical detection/recognition systems. The proposed approach focuses on the use of silicon (Si) as an optical coupling material and as a transducer module in SPR sensing schemes.; First, the thesis studies conditions of production and the main properties of Si-based SPR in a conventional prism-based scheme. A nearIR light (1100--2300 nm) is used to excite plasmons over a thin gold film, deposited on a Si prism, in the Kretschmann-Raether prism arrangement. Silicon-based SPR schemes display quite different regularities of plasmon excitation and polarity of the sensing response compared to glass-based ones. Such a difference is related to substantially different behavior of dispersion characteristics of silicon in comparison with glasses. However, the characteristics of Si-based SPR appear to be quite interesting for sensing tasks. In particular, the Si-based SPR sensor can provide higher spectral sensitivity and larger probe depth (1--2 mum), which makes it more effective for the detection of large objects such as cells and bacterial fragments.; Second, the thesis examines the SPR effect and its applications for sensing in several specific Si-based configurations. In particular, we studied SPR properties in combined (silicon prism/dielectric layer/gold film/dielectric sample medium) structures and established conditions of simultaneous excitation of two plasmon polariton modes (external and internal modes) over two interfaces of the SPR-supporting gold film. Here, the external mode corresponds to conventional plasmons excited over the metal/sample medium interface, whereas the internal plasmon polariton mode propagates over the gold/dielectric film interface. Based on a much higher refractive index of silicon compared to the dielectric film, this configuration permits narrow and well separated reflected intensity minima related to different plasmon polariton modes. It was also shown that the external mode demonstrates a highly sensitive response to a change in the refractive index of the sample medium, whereas the internal mode over the dielectric-gold interface is almost insensitive to medium parameters. Therefore, the internal mode could be used as an effective reference zero point for sensing. The presence of the reference point is especially important for sensing in field conditions and multi-channel tasks. (Abstract shortened by UMI.)