Hello Amrita,
I solve it using PML boundary condition and 5nm*5nm mesh. Could you please let me know what is the effective index of the 3rd mode you are getting? Is it less than nSiO2 (1.44)? Here is the file I simulated:
https://drive.google.com/drive/folders/1269qX-0XT5w4Rx-sISoPjcOdba0u_CXx?usp=sharing
Could you please check it or share your file?
Also, seeing the snapshots of the 3rd mode for all the 3 configurations I gave in the previous response, how may I understand that they are artifacts?
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