Optical sensing is a technique to study the interaction of molecules and has a lot of applications in sensors and detection of different chemical structures. Adding a new material to the surrounding space of a sensor causes a change in the resonance wavelength. Sensitive sensors should be designed in order to sense the added material by detection of small changes of refractive index. To have a proper and sensitive sensor, the interaction of light and material needs increase. Plasmonic nano particles have the ability of confining the light to the small regions. High confinement of light can increase the interaction of light and material which is used in plasmonic sensors. Reflectance or transmittance spectra are used to analyze the resonant sensors. The resonance wavelength is highly sensitive to the refractive index of surrounding material and this resonance wavelength shift can detect the refractive index changes. Plasmonic sensors are devided to two main categories named surface plasmon resonance sensors and cavity based sensors. Due to high sensitivity, these sensors can be used in bio applications. In this thesis, different kinds of plasmonic sensors in addition to their structures are discussed. Then three plasmonic sensors and their results are distinguished. In order to analyze the performance of the sensors, the results are compared to other recent articles. Key words: Plasmonics , Bio sensors , SPR sensors , Cavity based sensors
