Hello Archana,
I need to clarify a few things on your question, because you are in the OptiSystem section of the forum but talking about OptiFDTD. Additionally, it seems like you are talking about components which are not a thing in OptiFDTD the way they are in OptiSystem. In OptiFDTD you have to define the materials and design the actual structure that would make up your sensor in order to determine the reflectivity/transmissivity, it is not something you can simply set.
Can you show me what form you are working with and explain in more detail what you are trying to do?
Scott