Optical Sensor Essay

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2.8. Optical ring resonator based sensor performance metrics To compare different kinds of optical RR based sensors, it is necessary to define some performance metrics. The suitability of optical sensors for a particular application will depend on their performance across number of sensor requirements. Some metrics such as sensitivity, and sensor cost, can be defined numerically (either by means of experimental or theoretical calculations). Other metrics such as portability is more subjective or simply comparable but can have a significant influence on the commercial success of the methods. In this section a number of metrics that are typically considered to determine the performance of SOI RR based bio-chemical sensors are briefly…show more content…
However for the intensity interrogation scheme it becomes .Where, ΔI and Δn are the intensity variation and the surrounding effective refractive index. Sensitivity can be divided into two types, device sensitivity, and waveguide sensitivity. In practice, the sensitivity of device is defined by the wavelength shift per unit concentration of an analyte, it depends on its properties which is related to optical parameters longer resonant wavelength or smaller effective refractive index .The normalized sensitivity of cavity resonator device operating at different wavelengths is given by Whereas, the sensitivity of optical waveguide is given by the relation between the variations of effective index with respect to the waveguide parameter affected by the analyte to be detected. It is related to structure of the waveguide regardless of the devices type. The surrounding refractive index change is yielded by a refractive index variation of cover medium or by thickness variation of sensing layer []. It differs with the sensing mechanism whether homogeneous or surface sensing SH represents homogeneous, SS is surface sensing, Δnc change in cladding index, Δts change in add layer, and Δλ change in resonance wavelength 2.8.2. Selectivity Selectivity is a measure of how specific the response of a sensor is to the
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