{"id":308577,"date":"2023-09-26T09:17:36","date_gmt":"2023-09-26T09:17:36","guid":{"rendered":"\/forum\/forums\/topic\/grating-emission-angle-issue\/"},"modified":"2023-09-26T09:17:36","modified_gmt":"2023-09-26T09:17:36","slug":"grating-emission-angle-issue","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/grating-emission-angle-issue\/","title":{"rendered":"Grating emission angle issue"},"content":{"rendered":"<p>Hi, all<\/p>\n<div>I simulated the antenna emission angle by positioning the monitor to capture the calculated far-field data, and I verified the simulation results using theoretical formulas.<\/div>\n<div>&nbsp;<\/div>\n<div>The emission angle is defined as the coordinates of the maximum E^2 intensity in the far-field pattern.<\/div>\n<p><img loading=\"lazy\" decoding=\"async\" style=\"font-size: 14pt\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/09\/26-09-2023-1695717142-mceclip0.png\" width=\"426\" height=\"194\"><\/p>\n<div>The theoretical formula is given by sin(&theta;) = (neff * &lambda;) \/ &Lambda;, where &theta; represents the emission angle, &lambda; is the wavelength, and &Lambda; stands for the grating pitch. Following this, &theta; will be recalculated using Snell&#8217;s law because the grating is located in the cladding.<\/div>\n<div>&nbsp;<\/div>\n<div>The neff value is calculated using Lumerical MODE solver under two conditions:<\/div>\n<p>(1) Only Si waveguide &#8211;&gt; neff1=2.451<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/09\/26-09-2023-1695718304-mceclip2.png\" width=\"499\" height=\"497\"><\/p>\n<p>(2) SiN block and Si waveguide &#8211;&gt; neff2 = 2.455<\/p>\n<p>&nbsp;<img loading=\"lazy\" decoding=\"async\" style=\"font-size: 14pt\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/09\/26-09-2023-1695718172-mceclip1.png\" width=\"465\" height=\"488\"><\/p>\n<p>The simulated results were in agreement with the theoretical formulas, particularly for normal emission (&theta; = 0), under the conditions of SiN pitch at approximately 630 nm and a duty ratio of approximately 0.55.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/09\/26-09-2023-1695718992-mceclip3.png\" width=\"385\" height=\"256\"><\/p>\n<p>However, when I changed the SiN pitch to 750 nm (with a duty ratio of approximately 0.467), the emission angles calculated from the far-field results did not align with the values predicted by the theoretical formulas.<\/p>\n<p><img loading=\"lazy\" decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/09\/26-09-2023-1695719217-mceclip4.png\" width=\"310\" height=\"185\"><\/p>\n<p>Please help me analyze this issue further.<\/p>\n<p>Thank you.<\/p>\n<p>&nbsp;<\/p>\n","protected":false},"template":"","class_list":["post-308577","topic","type-topic","status-closed","hentry"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["289867","2592"],"_bbp_author_ip":["96.7.218.215"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["373"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["308577"],"_bbp_forum_id":["27833"],"_bbp_engagement":["2592","289867"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["308840"],"_bbp_last_active_id":["308840"],"_bbp_last_active_time":["2023-09-26 19:27:53"]},"test":"kenny-hh-chendeltaww-com"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/308577","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\/308577\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=308577"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}