Hi! SWAPANDEEP KAUR
May i ask which encoder decoder you are looking for? Encoders generally referred in OCDMA systems for encoding the data and provie chips to input signals.If this is your query then you can find this example in SAC OCDMA where fbg used to make encoder and code used is hadamard coding.Check the links for better understanding
http://staging.optiwave.com/forums/topic/sac-ocdma-system/
http://staging.optiwave.com/forums/topic/sac-ocdma-4/
Go fo the first link for official SAC OCDMA example and then second for Detailed discussion of coding.
In case you want to incorporate matlab, you can do that so to implement OOC, prime codes etc.