Methods for providing stable optical signals in dual wavelength referenced LED based sensors

In general LED based dual wavelength referenced intensity-modulated optical fiber sensors do not take account of the thermal drifts of the LED source(s). An optical design concept termed wavelength thermal matching is described that can be applied to extract a pair of stable optical signals from the emission of a single LED. This strategy ensures the selection of two separate wavelength bands within which the optical signal variations due to LED thermal effects will be very similar. Hence the application of wavelength thermal matching principle in the design of a dual wavelength referenced system provides referencing effectiveness against both the optical propagation losses and the optical source fluctuations.<>