{"id":395023,"date":"2024-11-22T19:05:54","date_gmt":"2024-11-22T19:05:54","guid":{"rendered":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/395023\/"},"modified":"2024-11-22T19:05:54","modified_gmt":"2024-11-22T19:05:54","slug":"395023","status":"publish","type":"reply","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/395023\/","title":{"rendered":"Reply To: FDE : Simulation waveguides with electrodes"},"content":{"rendered":"<p>&lt;p&gt;Hi Sara,&lt;\/p&gt;&lt;p&gt;In my experience, I see a lot of spurious modes in the simulation like PML modes when considering the electrodes. The PML modes are automatically removed from the simulation, but if there are a large number of these modes (having higher effective index than the physical modes), then even though they are discarded (from the Mode List) they are still counted as modes (solutions) by the solver when it&#8217;s solving the eigenmode equations. So, if you have a low &#8220;number of trial modes&#8221; and the solver finds that many PML modes, it no longer will look for modes even though you haven&#8217;t found the physical modes of the device. And you will see a message saying &#8220;No physical modes found&#8221;.&lt;\/p&gt;&lt;p&gt;I will recommend running the simulation without the electrodes first as you have already done. If the effective index looks reasonable to you, then note this down. Next, when you consider the electrodes, use the &#8220;&lt;span style=&#8221;text-decoration: underline;&#8221;&gt;<strong>search near n<\/strong>&lt;\/span&gt;&#8221; option, &lt;span style=&#8221;text-decoration: underline;&#8221;&gt;<strong>uncheck use max index<\/strong>&lt;\/span&gt;, and then use the value from the previous run in the field &#8220;&lt;span style=&#8221;text-decoration: underline;&#8221;&gt;<strong>n<\/strong>&lt;\/span&gt;&#8221; to find modes near this effective index value. If you still don&#8217;t see any modes, try increasing the &#8220;<strong>number of trial modes<\/strong>&#8220;. Please feel free to let me know if this doesn&#8217;t work. Thank you!&lt;\/p&gt;&lt;p&gt;<img loading=\"lazy\" decoding=\"async\" src=\"https:\/\/innovationspace.ansys.com\/forum\/wp-content\/uploads\/sites\/2\/2024\/11\/22-11-2024-1732302258-mceclip0.png\" width=\"441\" height=\"625\" \/>&lt;\/p&gt;&lt;p&gt;Regards,&lt;br&gt;Amrita&lt;\/p&gt;<\/p>\n","protected":false},"template":"","class_list":["post-395023","reply","type-reply","status-publish","hentry"],"aioseo_notices":[],"aioseo_head":"\n\t\t<!-- All in One SEO 4.9.10 - aioseo.com -->\n\t<meta name=\"description\" content=\"Hi Sara,In my experience, I see a lot of spurious modes in the simulation like PML modes when considering the electrodes. The PML modes are automatically removed from the simulation, but if there are a large number of these modes (having higher effective index than the physical modes), then even though they are discarded (from\" \/>\n\t<meta name=\"robots\" content=\"max-image-preview:large\" \/>\n\t<link rel=\"canonical\" href=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/395023\/\" \/>\n\t<meta name=\"generator\" content=\"All in One SEO (AIOSEO) 4.9.10\" \/>\n\t\t<meta property=\"og:locale\" content=\"en_US\" \/>\n\t\t<meta property=\"og:site_name\" content=\"Ansys Learning Forum | Ansys Innovation Space\" \/>\n\t\t<meta property=\"og:type\" content=\"article\" \/>\n\t\t<meta property=\"og:title\" content=\"Reply To: FDE : Simulation waveguides with electrodes | Ansys Learning Forum\" \/>\n\t\t<meta property=\"og:description\" content=\"Hi Sara,In my experience, I see a lot of spurious modes in the simulation like PML modes when considering the electrodes. The PML modes are automatically removed from the simulation, but if there are a large number of these modes (having higher effective index than the physical modes), then even though they are discarded (from\" \/>\n\t\t<meta property=\"og:url\" content=\"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/395023\/\" \/>\n\t\t<meta property=\"article:published_time\" content=\"2024-11-22T19:05:54+00:00\" \/>\n\t\t<meta property=\"article:modified_time\" content=\"2024-11-22T19:05:54+00:00\" \/>\n\t\t<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n\t\t<meta name=\"twitter:title\" content=\"Reply To: FDE : Simulation waveguides with electrodes | Ansys Learning Forum\" \/>\n\t\t<meta name=\"twitter:description\" content=\"Hi Sara,In my experience, I see a lot of spurious modes in the simulation like PML modes when considering the electrodes. 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The PML modes are automatically removed from the simulation, but if there are a large number of these modes (having higher effective index than the physical modes), then even though they are discarded (from","og:url":"https:\/\/innovationspace.ansys.com\/forum\/forums\/reply\/395023\/","article:published_time":"2024-11-22T19:05:54+00:00","article:modified_time":"2024-11-22T19:05:54+00:00","twitter:card":"summary_large_image","twitter:title":"Reply To: FDE : Simulation waveguides with electrodes | Ansys Learning Forum","twitter:description":"Hi Sara,In my experience, I see a lot of spurious modes in the simulation like PML modes when considering the electrodes. 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