{"id":290762,"date":"2023-06-28T14:48:38","date_gmt":"2023-06-28T14:48:38","guid":{"rendered":"\/forum\/forums\/topic\/negative-imaginary-index-in-material-data-what-to-interpret\/"},"modified":"2023-06-28T14:48:38","modified_gmt":"2023-06-28T14:48:38","slug":"negative-imaginary-index-in-material-data-what-to-interpret","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/negative-imaginary-index-in-material-data-what-to-interpret\/","title":{"rendered":"Negative imaginary index in material data- what to interpret?"},"content":{"rendered":"<p>I have been using the material from the database &#8220;SiO2 (Glass) &#8211; Palik&#8221; at wavelength 2um. I noticed the imaginary n has&nbsp; value of -1.11022e-16. It has resulted in some discrepency like negative absorption in RTA analysis. I always assumed Lumerical considers index or permittivity as n= real(n)+i*imag(n) and hence negative imag(n) would be considered gain for the system. So my query is-<\/p>\n<p>1. How to correctly model the material in such case to consider loss in stead of gain ( which I believe should be the case for any real dielectric material)?<br \/>2. If I want to exclude the imaginary part altogether while keep using the database value (real parts only), is there a way to set it up in the simulation?<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/28-06-2023-1687963095-mceclip0.png\"><\/p>\n","protected":false},"template":"","class_list":["post-290762","topic","type-topic","status-closed","hentry","topic-tag-material-properties"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["284076","2592"],"_bbp_author_ip":["23.206.193.146"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["371"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["290762"],"_bbp_forum_id":["27833"],"_bbp_engagement":["2592","284076"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["290791"],"_bbp_last_active_id":["290791"],"_bbp_last_active_time":["2023-06-28 17:49:22"]},"test":"sahas2vcu-edu"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/290762","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\/290762\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=290762"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}