Optical fiber temperature sensor based on refractive index variation technique

The optical fiber technology is an emerging field which seems to have enormous applications in sensor area besides communications. Temperature sensors based on refractive index variation in an optical fiber are under investigation. The refractive index of the uncladded portion of the fiber varies according to the temperature variation. The intensity modulated optical source is used to launch optical signal in the fiber. At the uncladded portion of the fiber, the cladding is provided by the air mixture which is highly temperature dependent. Any change in temperature results into output power variation at the detector which is directly calibrated in terms of {dollar}spcirc{dollar}C. The experimental method of temperature measurement has been developed by using uncladded portion of the fiber inside a chamber. Also, the adjustment of uncladded fiber length l is investigated in order to obtain the maximum temperature and its accuracy. Temperature distribution inside the chamber is obtained by moving the fiber at different locations.