{"id":287872,"date":"2023-06-09T09:19:11","date_gmt":"2023-06-09T09:19:11","guid":{"rendered":"\/forum\/forums\/topic\/comparing-a-post-bragg-grating-with-a-corrugated-bragg-grating-mode-converge\/"},"modified":"2023-06-09T09:19:11","modified_gmt":"2023-06-09T09:19:11","slug":"comparing-a-post-bragg-grating-with-a-corrugated-bragg-grating-mode-converge","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/comparing-a-post-bragg-grating-with-a-corrugated-bragg-grating-mode-converge\/","title":{"rendered":"Comparing a &#8216;post&#8217; bragg grating with a corrugated bragg grating &#8211; mode converge"},"content":{"rendered":"<p>Hi,<\/p>\n<p>I am trying to simulate the two following bragg gratings, the first being a corrugated (&#8216;standard&#8217;) bragg grating and the second being a &#8216;post&#8217; bragg grating:<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/09-06-2023-1686300727-mceclip0.png\"><\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/09-06-2023-1686300743-mceclip1.png\"><\/p>\n<p>After a few attempts, I have managed to correctly simulate the corrugated grating with the characteristic results. However I am stuck simulating the second (&#8216;post&#8217;) grating. One of the things troubling me is that the mode convergence sweep doesn&#8217;t converge: <img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/09-06-2023-1686300985-mceclip2.png\"><\/p>\n<p>It seems to me that since the structure is different, multiple modes are present in the post section of the &#8216;post&#8217; bragg grating, in contrast to the corrugated grating which is engineered to only carry a single mode in both sections (waveguide and corrugated). Could the EME solver have trouble with that? I have tried limiting the # of modes searched in the EME solver settings, but this doesn&#8217;t fix it (also using 50 instead of 6 modes):<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/09-06-2023-1686301187-mceclip3.png\"><\/p>\n<p>I have tried using PML (to avoid the unphysical modes being found with metal boundaries), but that didn&#8217;t change much.<\/p>\n<p>I made sure to select the correct (Fundamenta TE) Modes at both ports.&nbsp;<\/p>\n<p>&nbsp;<\/p>\n<p>I&#8217;d be very grateful for some piece of advice!<\/p>\n<p>Thanks in advance,<\/p>\n<p>Jasper<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"template":"","class_list":["post-287872","topic","type-topic","status-closed","hentry","topic-tag-BraggGrating-1","topic-tag-EME-1","topic-tag-photonics"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["268158","2592"],"_bbp_author_ip":["23.217.200.46"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["403"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["287872"],"_bbp_forum_id":["27833"],"_bbp_engagement":["2592","268158"],"_bbp_voice_count":["2"],"_bbp_reply_count":["3"],"_bbp_last_reply_id":["288217"],"_bbp_last_active_id":["288217"],"_bbp_last_active_time":["2023-06-12 14:50:35"]},"test":"jasper-wiersdorffhhi-fraunhofer-de"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/287872","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics"}],"about":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/types\/topic"}],"version-history":[{"count":0,"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/287872\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=287872"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}