{"id":433739,"date":"2025-06-10T13:51:24","date_gmt":"2025-06-10T13:51:24","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/how-to-get-the-bend-loss\/"},"modified":"2025-06-10T13:51:24","modified_gmt":"2025-06-10T13:51:24","slug":"how-to-get-the-bend-loss","status":"publish","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/how-to-get-the-bend-loss\/","title":{"rendered":"How to get the bend loss"},"content":{"rendered":"<p>&lt;p&gt;Hi, how to get the bend loss has bothered me for a long time. I have try many solvers in Lumerical. For example, when I used the FDTD solver to simulate a bent waveguide, I set up power monitors at the input and output &lt;span style=&#8221;font-family: Calibri;&#8221;&gt;ports&lt;\/span&gt;&nbsp;of a 90&deg; bent waveguide and used a formula to calculate the bending loss. However, as the bending radius gradually increased to approximately 50 &mu;m, the FDTD simulation of the bent waveguide became very slow and always terminated prematurely.&nbsp;&lt;span style=&#8221;font-family: Calibri;&#8221;&gt;The issue of large-bend waveguides requiring more operating memory cannot be resolved on my device.&lt;\/span&gt;&lt;\/p&gt;&lt;p class=&#8221;MsoNormal&#8221; align=&#8221;justify&#8221;&gt;&lt;span style=&#8221;font-family: Calibri;&#8221;&gt;So a&lt;\/span&gt;fter reviewing the official documentation, I switched to &lt;span style=&#8221;font-family: Calibri;&#8221;&gt;use &lt;\/span&gt;the FDE solver. However, the FDE solver has an issue: as mentioned in responses to other posts, the bending loss calculated by FDE does not include scattering loss&lt;span style=&#8221;font-family: Calibri;&#8221;&gt;. &lt;\/span&gt;Additionally, based on my simulation results, the bending loss obtained from FDE simulations is consistently at the 10\u207b\u2077 order of magnitude or even smaller.&nbsp;&lt;span style=&#8221;font-family: Calibri;&#8221;&gt;What&lt;\/span&gt;&lt;span style=&#8221;font-family: Calibri;&#8221;&gt;&rsquo;&lt;\/span&gt;&lt;span style=&#8221;font-family: Calibri;&#8221;&gt;s the problem? &lt;\/span&gt;&lt;\/p&gt;&lt;p class=&#8221;MsoNormal&#8221; align=&#8221;justify&#8221;&gt;I had to switch to the current FEEM. When running the official case, the bending loss was 278 dB\/cm, consistent with the results on the official website. However, when I modified the structural parameters and material parameters of the waveguide while keeping other settings unchanged, and only adjusted the range of the bending simulation region and the size of the bending radius, with the bending radius set to 10 &mu;m, the resulting loss is always at the 10^-10 order of magnitude, and the results of each simulation &lt;span style=&#8221;font-family: Calibri;&#8221;&gt;always change&lt;\/span&gt;, not being a constant value&lt;span style=&#8221;font-family: Calibri;&#8221;&gt;, even I don&lt;\/span&gt;&lt;span style=&#8221;font-family: Calibri;&#8221;&gt;&rsquo;&lt;\/span&gt;&lt;span style=&#8221;font-family: Calibri;&#8221;&gt;t adjust something other, just run again&lt;\/span&gt;.&lt;\/p&gt;&lt;p class=&#8221;MsoNormal&#8221; align=&#8221;justify&#8221;&gt;I have posted several questions about bending loss simulation, but I still haven&#8217;t figured out how to address these issues to obtain accurate loss simulation results. Could you please help me resolve these issues?&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-433739","topic","type-topic","status-publish","hentry","topic-tag-bend-1","topic-tag-bending","topic-tag-bendingloss-1","topic-tag-FDE-1","topic-tag-FEEM-1"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_forum_id":["27833"],"_bbp_topic_id":["433739"],"_bbp_subscription":["438269","501387"],"_bbp_author_ip":["59.125.68.205"],"_bbp_last_reply_id":["434184"],"_bbp_last_active_id":["434184"],"_bbp_last_active_time":["2025-06-16 10:02:47"],"_bbp_reply_count":["1"],"_bbp_reply_count_hidden":["0"],"_bbp_voice_count":["2"],"_bbp_engagement":["438269","501387"],"_btv_view_count":["359"],"_bbp_topic_status":["unanswered"],"_bbp_notification_enabled":["473055"]},"test":"a15ce5430abdf9961861d8d2706964f47bb14a88"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/433739","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\/433739\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=433739"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}