{"id":254,"date":"2023-06-08T11:02:19","date_gmt":"2023-06-08T09:02:19","guid":{"rendered":"https:\/\/logbooks.ifosim.org\/finesse\/?p=254"},"modified":"2023-06-08T11:02:19","modified_gmt":"2023-06-08T09:02:19","slug":"adding-higher-order-modes-to-finesse3-using-old-etpf-imc-design-as-an-example","status":"publish","type":"post","link":"https:\/\/logbooks.ifosim.org\/finesse\/2023\/06\/08\/adding-higher-order-modes-to-finesse3-using-old-etpf-imc-design-as-an-example\/","title":{"rendered":"Adding higher order modes to Finesse3 using old ETPF IMC design as an example"},"content":{"rendered":"\n

For analysing the performance of a Mode Cleaner (MC) we need a “dirty” Beam as an input to make sure that our MC is filtering out higher order modes. <\/p>\n\n\n\n

To create a dirty beam we first add a laser to our system, than enable higher modes and add a mixture of new and higher order modes<\/p>\n\n\n\n

l laser1 P=1 <\/strong># input laser with P = 1.0 W<\/em>\nmodes(maxtem=1)<\/strong> # allow higher order modes, here up to order 1<\/em>\ntem(l1, 0, 0, 1, 0.0)<\/strong> # TEM00 mode with P=1\/3 Laserpower at 0 phaseshift<\/em>\ntem(l1, 0, 1, 2, 45.0)<\/strong> # TEM01 mode with P=2\/3 Laserpower at 45 phaseshift <\/em><\/code><\/pre>\n\n\n\n
To define detectors before and after the cavity (see cavity below) we add a amplitude detector at the Input and output of our cavity, with specific detection modes<\/p>\n\n\n\n
#INPUT<\/em>\nad inTEM00 IC.p1.i f=0 n=0 m=0 <\/strong>#Amplitude detector for TEM00 at IC input<\/em>\nad inTEM01 IC.p1.i f=0 n=0 m=1 <\/strong>#Amplitude detector for TEM01 at IC input\n<\/em>\n#OUTPUT<\/em>\nad outTEM00 OC.p4.o f=0 n=0 m=0<\/strong> #Amplitude detector for TEM00 at OC output<\/em>\nad outTEM01 OC.p4.o f=0 n=0 m=1<\/strong> #Amplitude detector for TEM01 at OC output<\/em><\/code><\/pre>\n\n\n\n
When plotting these Detectors we can see a dirty input beam with a lot more TEM01 mode in it. When ramping through the HR.phi we can see that the cavity is resonant for each mode at different stages<\/p>\n\n\n\n
\n
\"\"<\/figure>\n\n\n\n
\"\"<\/figure>\n<\/figure>\n\n\n\n
The setup<\/strong><\/p>\n\n\n\n
For the simulation above to work we have to define the rest of the cavity with the different mirrors and spaces, here I added an old triangle MC design for ETPF that was designed by Annabel Wolf as a Master Thesis “Optical System Design of the Einstein Telescope Pathfinder”<\/p>\n\n\n\n
\"\"<\/figure>\n\n\n\n
Here is the code for those who are interested<\/p>\n\n\n\n
bs IC T=0.0025 L=0 alpha=83.90625 #IC mirror <\/em>\nbs OC T=0.0025 L=0 alpha=83.90625 #OC mirror<\/em>\nbs HR T=10e-6 L=0 alpha=12.1875 Rc=6.7 #HR curved mirror<\/em>\n\ns s1 l1.p1 IC.p1 L=0.1 #Laser -> IC<\/em>\n\ns sBase IC.p3 OC.p2 L=0.2 #IC -> OC<\/em>\ns sSide1 IC.p4 HR.p1 L=2.8 #IC -> HR<\/em>\ns sSide2 HR.p2 OC.p1 L=2.8 #HR -> OC<\/em>\ncav MC IC.p4 #building the cavity<\/em><\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"
For analysing the performance of a Mode Cleaner (MC) we need a “dirty” Beam as an input to make sure that our MC is filtering out higher order modes. To create a dirty beam we first add a laser to our system, than enable higher modes and add a mixture of new and higher order […]<\/p>\n","protected":false},"author":80,"featured_media":0,"comment_status":"open","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"ssl_alp_hide_revisions":false,"footnotes":"","ssl_alp_hide_crossreferences_to":false},"categories":[1],"tags":[],"ssl-alp-coauthor":[50],"class_list":["post-254","post","type-post","status-publish","format-standard","hentry","category-uncategorised"],"_links":{"self":[{"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/posts\/254","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/users\/80"}],"replies":[{"embeddable":true,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/comments?post=254"}],"version-history":[{"count":1,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/posts\/254\/revisions"}],"predecessor-version":[{"id":267,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/posts\/254\/revisions\/267"}],"wp:attachment":[{"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/media?parent=254"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/categories?post=254"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/tags?post=254"},{"taxonomy":"ssl-alp-coauthor","embeddable":true,"href":"https:\/\/logbooks.ifosim.org\/finesse\/wp-json\/wp\/v2\/ssl-alp-coauthor?post=254"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}