Process and device including a fixed cavity with a free spectral range for characterizing an optical source

A method for characterizing an optical source, the optical source comprising a fixed cavity having a free spectral range, the method comprising:

• generating a first radiation by the source while exploring different states of the source, the different states of the source being distinguished by a difference of a physical parameter of the source which has an influence on the wavelength of said first radiation emitted by the source;
• receiving at least a part of said first radiation by at least one sensor, said at least one sensor comprising a Fabry-Perot etalon followed by a photodiode;
• measuring a signal, for each of the explored states of the source using said at least one sensor, as a function of the at least one part of said first radiation received by said at least one sensor at this explored state of the source;
• determining or recording a constant (b) modulo of the free spectral range of the fixed cavity expressed in units of a first data item, which is representative of the wavelength of said first radiation;
• and
• using the signal measured by said at least one sensor for each of the explored states of the source for calculating the first data item, which is representative of the wavelength of said first radiation, the calculation comprising, for each of the explored states of the source, selecting a value of the first data item, and eliminating values of the first data item that do not correspond to the constant (b) modulo of the free spectral range of the fixed cavity expressed in the units of the first data item.