{"id":287878,"date":"2023-06-09T09:35:50","date_gmt":"2023-06-09T09:35:50","guid":{"rendered":"\/forum\/forums\/topic\/fwhm-and-reflectance-of-bragg-grating-unexpectedly-high\/"},"modified":"2023-06-09T09:35:50","modified_gmt":"2023-06-09T09:35:50","slug":"fwhm-and-reflectance-of-bragg-grating-unexpectedly-high","status":"closed","type":"topic","link":"https:\/\/innovationspace.ansys.com\/forum\/forums\/topic\/fwhm-and-reflectance-of-bragg-grating-unexpectedly-high\/","title":{"rendered":"FWHM and Reflectance of Bragg Grating unexpectedly high"},"content":{"rendered":"<p>Hello,<\/p>\n<p>I simulated the following bragg grating:<\/p>\n<p>(Sketch:)<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/09-06-2023-1686302543-mceclip1.png\"><\/p>\n<p>(Setup in Lumerical:)<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/09-06-2023-1686302524-mceclip0.png\"><\/p>\n<p>Since the sections are both single mode, the mode convergence sweep works out fine. I get the following results:<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/09-06-2023-1686302674-mceclip2.png\"><\/p>\n<p>The spectrum has a typical bragg grating form, however the FWHM and Reflectance are too high compared to measurements and simulations with other programs. For example, for a corrugation depth of 0.075&micro;m, the FWHM is about 2.3nm when it should be about 0.7nm and the reflectivity is approximately 1 when it should be significantly lower (0.7). I have used the same geometry setup and the same # of periods. The grating period was calculated using the approximation via the average neffs of the fundamental TE modes of each cell: (neff=sqrt((neff_l1^2)*(1-duty_cycle)+(neff_l2^2)*duty_cycle). These are my EME settings:<\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/09-06-2023-1686303146-mceclip3.png\"><\/p>\n<p><img decoding=\"async\" src=\"\/forum\/wp-content\/uploads\/sites\/2\/2023\/06\/09-06-2023-1686303184-mceclip4.png\"><\/p>\n<p>Could this perhaps be caused by the integrated wavelength sweep feature in EME? What is going on here?<\/p>\n<p>I&#8217;d appreciate some help.<\/p>\n<p>Thanks,<\/p>\n<p>Jasper<\/p>\n","protected":false},"template":"","class_list":["post-287878","topic","type-topic","status-closed","hentry","topic-tag-BraggGrating-1","topic-tag-photonics"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["268158","2592"],"_bbp_author_ip":["23.47.145.29"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_btv_view_count":["532"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["287878"],"_bbp_forum_id":["27833"],"_bbp_engagement":["2592","268158"],"_bbp_voice_count":["2"],"_bbp_reply_count":["1"],"_bbp_last_reply_id":["287990"],"_bbp_last_active_id":["287990"],"_bbp_last_active_time":["2023-06-09 17:58:14"]},"test":"jasper-wiersdorffhhi-fraunhofer-de"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/287878","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\/287878\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=287878"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}