{"id":362012,"date":"2024-04-12T17:21:54","date_gmt":"2024-04-12T17:21:54","guid":{"rendered":"\/forum\/forums\/reply\/362012\/"},"modified":"2024-04-12T17:21:54","modified_gmt":"2024-04-12T17:21:54","slug":"362012","status":"publish","type":"reply","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/362012\/","title":{"rendered":"Reply To: FDTD:: simulation of directional coupler"},"content":{"rendered":"<p>&lt;p&gt;Here is a summary of the two rounds of running:&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/04\/12-04-2024-1712942503-final3-0.JPG\" alt=\"\" \/>&lt;\/p&gt;&lt;p&gt;1. boundary X\/Y standard = 64\/32 layer, Z is Metal:&lt;\/p&gt;&lt;p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/04\/12-04-2024-1712941408-final3-4.JPG\" alt=\"\" width=\"386\" height=\"167\" \/>&lt;\/p&gt;&lt;p&gt;2. boundary X standard=64, Y steep angle = 64, Z standard =16:&lt;\/p&gt;&lt;p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/04\/12-04-2024-1712941499-final4-0.JPG\" alt=\"\" width=\"568\" height=\"244\" \/>&lt;\/p&gt;&lt;p&gt;Neither of them converge. They both diverge after reaching shutoff = 2~4e-3&lt;\/p&gt;&lt;p&gt;Using Standard 64 and 16 layers of PML at X\/Z boundary is enough, the light in PML will decrease to lower than or near e-4:&lt;\/p&gt;&lt;p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/04\/12-04-2024-1712941782-final3-5.JPG\" alt=\"\" width=\"282\" height=\"180\" \/><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/04\/12-04-2024-1712941798-final4-1.JPG\" alt=\"\" width=\"242\" height=\"184\" \/>&lt;\/p&gt;&lt;p&gt;But in Y min boundary where it faces the scatter light from input S bend WG, the absorption is not good, especially the steep angle one:&lt;\/p&gt;&lt;p&gt;Steep Angle = 64 layer:&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/04\/12-04-2024-1712942378-final4-2.JPG\" alt=\"\" \/>&lt;\/p&gt;&lt;p&gt;Standard layer=32:&lt;\/p&gt;&lt;p&gt;<img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2024\/04\/12-04-2024-1712941888-final3-3.JPG\" alt=\"\" \/>&lt;\/p&gt;&lt;p&gt;Right now the only side where PML can not effectively absorb is Y min boundary. Do you think it&#8217;s the reason causing the divergence? Let me know why 64 layer steep angle gives a worse result in absorption than standard 32 layers and how I can further optimize. Thanks.&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-362012","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"acf":[],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/replies\/362012","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\/362012\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=362012"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}