Optical Bandpass Filter (Gaussian)

Dear readers,

I want to model a Optical Bandpass Filter (Gaussian) in matlab.
I tried to search for its equation/transfer function but unable to find it. Help is requested from the forum members in this regard.

Thanks
This is my first attempt to model a filter

Start from the equations for transmission of the Fabry-Perot interferometer:

https://en.wikipedia.org/wiki/Fabry%...interferometer
https://duepublico.uni-duisburg-esse...0Resonator.pdf