Optical fiber sensors
Exercice 2
Here is a fiber thermometer with a Fabry-Pérot cavity (FP) placed at the extremity of the fiber as shown on the Figure below. The cavity's mirrors are supposed to all have the same reflection coefficient and to be insensitive to temperature's variations.
Figure 24: Fiber thermometer
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Question
If we assume that the FP cavity is filled up with a material whose index is called n and that the cavity length is L, define the phase difference
inserted in the cavity.
Question
What impact has a variation of temperature on the answer of the FP?
Question
How does the finesse vary according to the refractive index of the liquid?