Ayan,
These are general design topics…We are here to provide support on how to use the product and will do so if you have specific questions about the products.
For photonic crystal design We have a number of webinars available through the support drop down which will be of use to you.
Gain materials are supported through either Lorentz-Drude models or a positive imaginary component to the refractive index. One note on gain materials is saturation is not within the model so caution must be used as the simulation could easily become unstable in this domain.
Scott