{"id":350179,"date":"2024-02-09T17:07:22","date_gmt":"2024-02-09T17:07:22","guid":{"rendered":"\/forum\/forums\/reply\/350179\/"},"modified":"2024-02-09T17:07:22","modified_gmt":"2024-02-09T17:07:22","slug":"350179","status":"publish","type":"reply","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/350179\/","title":{"rendered":"Reply To: Diverging simulation when going from long to short wavelength"},"content":{"rendered":"<p>&lt;p&gt;Hi Anita, thank you for your quick reply.This is a single wavelength simulation (simulation bandwidth of 0.3 um which is the standard set by Lumerical FDTD, I also tried reducing this to 0.1 um but that did not resolve the issue). The materials used are Silicon Nitride (for the waveguide) and silicon dioxide (for the cladding).&lt;\/p&gt;&lt;p&gt;I think you may be correct about the issue being related to the material fitting, but I am not sure exactly how this is causing the issue. As I mentioned, the simulation runs fine for a longer wavelength and I use similar values for the fit tolerance, number of fitting coefficients and the fitting range.&nbsp;&lt;\/p&gt;&lt;p&gt;I have attached some images from the movie monitor that show the issue.&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/02\/09-02-2024-1707498369-1.PNG\" alt=\"\" \/><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/02\/09-02-2024-1707498392-2.PNG\" alt=\"\" \/><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/02\/09-02-2024-1707498407-3.PNG\" alt=\"\" \/>&lt;\/p&gt;&lt;p&gt;Kind regards,&lt;\/p&gt;&lt;p&gt;Daniel&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-350179","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"acf":[],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/350179","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/reply"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/350179\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=350179"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}