{"id":285431,"date":"2023-05-24T07:02:09","date_gmt":"2023-05-24T07:02:09","guid":{"rendered":"\/forum\/forums\/topic\/fundamental-mode-waveguide-in-fdtd\/"},"modified":"2023-05-24T07:02:09","modified_gmt":"2023-05-24T07:02:09","slug":"fundamental-mode-waveguide-in-fdtd","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/fundamental-mode-waveguide-in-fdtd\/","title":{"rendered":"Fundamental Mode Waveguide in FDTD"},"content":{"rendered":"<p class=\"MsoNormal\"><span lang=\"EN-US\">Hi,<\/span><\/p>\n<p class=\"MsoNormal\"><span lang=\"EN-US\">I am trying to design a Y-branch combiner that connects three single-mode waveguides(only fundamental TE and TM modes allowed). <\/span><\/p>\n<p class=\"MsoNormal\"><span lang=\"EN-US\">First, I used MODE to check whether a waveguide is single-mode. As shown in the attachment, the waveguide only showed two fundamental guided modes (TE &amp; TM) when the number of mesh cells is set to 800 in x and y.<img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/05\/24-05-2023-1684911618-1.png\" alt=\"\"><\/span><\/p>\n<p class=\"MsoNormal\"><span lang=\"EN-US\"><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/05\/24-05-2023-1684911676-2.png\" alt=\"\"><\/span><\/p>\n<p class=\"MsoNormal\"><span lang=\"EN-US\">Thus, I used this waveguide to design a Y branch and set a fundamental TM mode source injecting from the right-upper port(Please refer to the attachment) in FDTD. However, I found the output port showed a mode that is neither fundamental TE nor TM mode. I think only the fundamental TE and TM modes are allowed and will be guided in this waveguide. Why does this happen? Is this because the mesh of FDTD is too coarse?<\/span><\/p>\n<p class=\"MsoNormal\"><span lang=\"EN-US\"><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/05\/24-05-2023-1684911693-3.png\" alt=\"\"><\/span><\/p>\n","protected":false},"template":"","class_list":["post-285431","topic","type-topic","status-closed","hentry","topic-tag-mesh"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["285687","2592","284692"],"_bbp_author_ip":["23.39.172.22"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["594"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["285431"],"_bbp_forum_id":["27833"],"_bbp_engagement":["2592","284692","285687"],"_bbp_voice_count":["3"],"_bbp_reply_count":["4"],"_bbp_last_reply_id":["286193"],"_bbp_last_active_id":["286193"],"_bbp_last_active_time":["2023-05-29 16:42:28"]},"test":"pyhsiaoutexas-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/285431","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\/285431\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=285431"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}