In Chapter 2, we have seen that a tilt
in the grating is associated with an excess loss. In a first approximation
these losses are assumed to be frequency independent and they are included in a
loss matrix Taj defined as
|
(3-24) |
The similarity with the pure
propagation matrix allows to define a new propagation matrix that takes account
of the loss :
|
(3-25) |
The loss matrix can be adapted to other
types of loss, frequency dependent or not via the parameter a. The recursion
equation becomes in this case
|
(3-26) |
The reconstruction for FBGs
experiencing losses, which can be described with the loss matrix Ta,j, is possible with the layer-peeling method by using the recursive
equation (3-26) instead of (3-13).
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