Hello Devika,
What version of the product are you using?
There is public access to the tutorials on using the OptiFDTD product for photonic crystal design (<a href=”https://optiwave.com/category/optifdtd-manuals/optifdtd-background-and-tutorials/a5-lesson-3-photonic-crystal-and-photonic-band-gap/”>https://optiwave.com/category/optifdtd-manuals/optifdtd-background-and-tutorials/a5-lesson-3-photonic-crystal-and-photonic-band-gap/</a>).
We also have a range of webinars that outline some of the basics of using the product (<a href=”https://optiwave.com/category/resources/webinars/”>https://optiwave.com/category/resources/webinars/</a>).
Scott