Hello Umer,
If you can implement the ring resonator using OptiBPM then you do not require MATLAB code at all. All You need to do then is that you can look for the co-simulation of OpyiBPM and Optisystem.
In case you are not able to implement it using OptiBPM then you have to write a code for it in MATLAB anfd interface the MATLAB module with Optisystem.
Regards