Sensorsystem mit mehreren Oberflächen für evaneszente Wellen

An evanescent wave sensor and method for use in analyzing one or more media, the sensor including a waveguide having first and second wave propagating surfaces. The waveguide propagates an input signal along the waveguide between the first and second surfaces. The first surface receives a first radiation signal which indicates the presence of a first analyte, and the second surface receives a second radiation signal representing one or both of a second analyte and a reference. The first and second surfaces can both be contacted with a single medium, or with two separate media, and one or more output signals can be detected.