2. Techniques for measuring essential characteristics

Most of the photodetector structures whose characteristics and measurement techniques are the subject of this document have circular sensitive surfaces. They have the same diameters as those of the fiber cores and propagation modes when placed and fixed against the output faces of the transmission fibers, inside a hermetically sealed housing. The user generally has no access to the surface exposed to the incident flux. Certain parameters, including absolute sensitivity, are therefore only directly accessible to the designer. The user only has access to the structure through a sample of fiber, known as the "seed fiber", or through a protective lens and/or glass.

In the previous paragraph, we outlined the essential characteristics of our current generators, based on theoretical and technological structural considerations:

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