Hi,<\/p>\n
I do face the following problem in 3D FDTD:<\/p>\n
In a layered\/stratified substrate, infinitely extended in the x-y-plane, with layer\/interface normals along the z-axis (easiest case: a single film\/slab\/layer of refractive material in air), I want to excite a specific mode propagating in the xy-plane.<\/p>\n
For a mode propagating only in one direction, say in the positive x-direction, I know I can achieve this using a mode source extended over the whole y-z-plane of the simulation space.<\/p>\n
However, I do want to excite the mode at a single point x0,y0 and to propagate it outwards from there in all directions within the x-y-plane. This “line source” would therefore extend over the complete z-axis, but only cover a single point x0,y0 in the x-y-plane.<\/p>\n
I am thinking of dipole-like emission patterns: For a TM\/TE mode with Ez\/Hz polarization, the emission would either be isotropic within the x-y-plane, similar to an electrical\/magnetical dipole with vertical (z) orientation. Alternatively, the emission pattern could also behave similar to a horizontal magnetical\/electrical dipole, forming dipole-lobes in the x-y-plane.<\/p>\n
However, in contrast to a single dipole source, this line source should only excite one single, distinctive, guided mode propagating in the substrate, and should not excite any other guided or unguided modes, like emission from the substrate. This source in fact would be equal to the varFDTD dipole source, but implemented in FDTD.<\/p>\n
To achieve this, I thought of calculating the mode profile using a mode monitor. Then, I would place lots of dipoles along the z-axis at point x0,y0 with their amplitudes (and possibly phases) adjusted to represent the mode profile along the z-axis.<\/p>\n
However, this would include retreiving the mesh structure to find the z-coordinates for all dipoles, discretizing the mode profile onto the dipoles and then placing lots of dipoles very close to each other, such that they may influence each other.<\/p>\n
Is there any easier, and possibly more accurate way to do this?<\/p>\n
Thank you for your help!<\/p>\n","protected":false},"template":"","class_list":["post-218831","topic","type-topic","status-closed","hentry","topic-tag-3d","topic-tag-dipole","topic-tag-fdtd","topic-tag-layers"],"aioseo_notices":[],"acf":[],"custom_fields":[{"0":{"_bbp_subscription":["250776","2592","55269"],"_bbp_author_ip":["204.2.243.141"]," _bbp_last_reply_id":["0"]," _bbp_likes_count":["0"],"_edit_lock":["1658232551:76739"],"_btv_view_count":["1395"],"_bbp_topic_status":["unanswered"],"_bbp_status":["publish"],"_bbp_topic_id":["218831"],"_bbp_forum_id":["27833"],"_bbp_engagement":["2592","55269","250776"],"_bbp_voice_count":["3"],"_bbp_reply_count":["11"],"_bbp_last_reply_id":["220178"],"_bbp_last_active_id":["220178"],"_bbp_last_active_time":["2022-07-25 15:39:27"]},"test":"stefan-appelwsi-tum-de"}],"_links":{"self":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/topics\/218831","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\/218831\/revisions"}],"wp:attachment":[{"href":"https:\/\/innovationspace.ansys.com\/forum\/wp-json\/wp\/v2\/media?parent=218831"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}