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MZI add drop (bragg gratings)

  1. Sep 6, 2008 #1

    I came across this mzi add drop function/device and need some help to to fully understand it.

    I attached a picture which shows the thing.

    Ok so, the first 50/50 coupler splits the intensities to the 2 arms with the bragg gratings, bragg gratings are adjusted(made) so that they reflect back lambda1, now as the 2 arms reflect back the lambda1s , these 2 intensities are now at the same 50/50 coupler getting ready to get splitted again. As the picture shows lambda1 is "only" going to "drop port 1".

    I can guess that the 2 lambda1s are phase shifted and then cancel each other out going to input port 1 and constructively added to drop port 1.
    But Im not sure. I dont see why they get different phase shifts. Does the coupling give them different phase shifts ?

    After the bragg gratings, the upper arm has a pi-phase shift function which shifts the upper lambdas, lambda2/3, and a new lambda1' is added from "output port 2". Lambda2/3 get constructively added to "output port1" with the added lambda1'.

    thx in advance.

    Attached Files:

  2. jcsd
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