Abstract: An optical detection system (100) for detecting biological, chemical or bio-chemical particles is described. The optical detection system (100) typically comprises a surface mode interference means. The surface mode interference means may comprise a layer (102) such as for example a metal layer like e.g. a gold layer. The surface mode interference means furthermore typically is adapted to create an interference effect between optical interface modes of the layer to detect optical changes in the vicinity of the layer (102). In this way, sample (106) occurring in the vicinity of the surface may be detected. The present invention furthermore relates to a method for performing optical detection and to a method for setting up an optical detection system wherein parameters are selected for tuning the surface mode interference means to a desired wavelength range and/or to a desired range of analyte refractive indices.