{"id":341,"date":"2025-08-27T20:11:29","date_gmt":"2025-08-27T11:11:29","guid":{"rendered":"https:\/\/www.hulinks.co.jp\/en\/?page_id=341"},"modified":"2025-10-07T17:32:07","modified_gmt":"2025-10-07T08:32:07","slug":"wide-infrared","status":"publish","type":"page","link":"https:\/\/www.hulinks.co.jp\/en\/tfcalc\/examples\/list-of-coating-design\/wide-infrared\/","title":{"rendered":"Wide Infrared Bandpass Filter"},"content":{"rendered":"\n<h1 class=\"wp-block-heading is-style-nostyle\">List of coating design exapmles<\/h1>\n\n\n\n<h2 class=\"wp-block-heading is-style-bottomline\">Wide Infrared Bandpass Filter<\/h2>\n\n\n\n<p>This coating is for light at normal incidence on a germanium substrate (index 4). The requirements are:<\/p>\n\n\n\n<ol style=\"list-style-type:upper-alpha\" class=\"wp-block-list\">\n<li>Transmittance &lt; 0.1% for wavelengths 2000-3000 nm<br><br><\/li>\n\n\n\n<li>Transmittance &gt; 99% for wavelengths 3300-5000 nm<br><br><\/li>\n\n\n\n<li>Transmittance &lt; 0.1% for wavelengths 5500-7000 nm<\/li>\n<\/ol>\n\n\n\n<p>The two coating materials are Ge and ZnS (indices 4.2 and 2.2). Although this coating could be designed by \u201cbrute force\u201d (just input the optimization targets and let needle\/tunneling find a design), a faster approach for wide bandpass filters is to (1) design short and long wave pass filters, (2) append the two filters, and (3) reoptimize. The procedure is illustrated here.<\/p>\n\n\n\n<p>First, starting with a single thin layer, the needle\/tunneling method was used to create a 31-layer long-wave pass filter using requirements A and B. The transmission in requirement A was reduced to 0.01% so that the final design can meet the 0.1% requirement. The performance is shown below.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"426\" height=\"239\" src=\"https:\/\/www.hulinks.co.jp\/en\/wp-content\/uploads\/sites\/2\/software\/tfcalc\/tf_wide_1.gif\" alt=\"\" class=\"wp-image-342\" \/><\/figure><\/div>\n\n\n<div style=\"height:10px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>Second, starting with a single thin layer, the needle\/tunneling method was used to create a 17-layer short-wave pass filter using requirements B and C. The performance is shown below.<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"423\" height=\"238\" src=\"https:\/\/www.hulinks.co.jp\/en\/wp-content\/uploads\/sites\/2\/software\/tfcalc\/tf_wide_2.gif\" alt=\"\" class=\"wp-image-343\" \/><\/figure><\/div>\n\n\n<div style=\"height:10px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>Third, experience shows that it is best to place the short-wave pass filter closest to the substrate and then to append the long-wave pass filter. (The needle\/tunneling method \u201cdiscovers\u201d this fact when the brute-force approach is used.) Before optimizing, the performance is:<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"423\" height=\"240\" src=\"https:\/\/www.hulinks.co.jp\/en\/wp-content\/uploads\/sites\/2\/software\/tfcalc\/tf_wide_3.gif\" alt=\"\" class=\"wp-image-344\" \/><\/figure><\/div>\n\n\n<div style=\"height:10px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>After optimizing this design, the final performance is:<\/p>\n\n\n<div class=\"wp-block-image\">\n<figure class=\"aligncenter size-full\"><img loading=\"lazy\" decoding=\"async\" width=\"422\" height=\"238\" src=\"https:\/\/www.hulinks.co.jp\/en\/wp-content\/uploads\/sites\/2\/software\/tfcalc\/tf_wide_4.gif\" alt=\"\" class=\"wp-image-345\" \/><\/figure><\/div>\n\n\n<div style=\"height:10px\" aria-hidden=\"true\" class=\"wp-block-spacer\"><\/div>\n\n\n\n<p>Here are the designs, with the first layer closest to the substrate and thickness given in nm. With a little more work, it may be possible to eliminated some thin layers.<\/p>\n\n\n\n<pre class=\"wp-block-code\"><code>          Short        Long       Bandpass\n    ZnS   83.39                     97.33\n    Ge    48.25                     48.60\n    ZnS  756.31                    761.47\n    Ge   403.51                    412.85\n    ZnS  710.33                    720.06\n    Ge   377.93                    382.28\n    ZnS  696.05                    705.03\n    Ge   370.17                    370.42\n    ZnS  696.91                    709.26\n    Ge   365.05                    358.23\n    ZnS  705.00                    718.52\n    Ge   361.44                    353.08\n    ZnS  719.03                    724.86\n    Ge   360.53                    360.01\n    ZnS  751.56                    710.47\n    Ge   328.61                    398.52\n    ZnS  369.01      158.71        564.95\n    Ge               124.38         40.79\n    ZnS              260.14        224.72\n    Ge                78.55        125.31\n    ZnS              149.33        133.58\n    Ge               102.25         98.28\n    ZnS              235.97        268.21\n    Ge               145.53        138.25\n    ZnS              279.07        238.01\n    Ge               128.80        125.48\n    ZnS              196.52        232.65\n    Ge                67.11         68.54\n    ZnS              159.26        168.55\n    Ge               132.16        150.14\n    ZnS              271.50        254.28\n    Ge               144.32        125.25\n    ZnS              281.93        307.19\n    Ge               149.33        165.16\n    ZnS              278.65        256.22\n    Ge               140.79        133.04\n    ZnS              271.93        289.60\n    Ge               147.16        147.63\n    ZnS              276.89        266.04\n    Ge               138.39        134.34\n    ZnS              271.52        265.60\n    Ge               152.12        156.86\n    ZnS              291.92        294.15\n    Ge               135.69        123.17\n    ZnS              249.93        250.12\n    Ge               166.98        178.96\n    ZnS              553.73        528.64<\/code><\/pre>\n","protected":false},"excerpt":{"rendered":"<p>List of coating design exapmles Wide Infrared Bandpass Filter This coating is for light at normal incidence on a germanium substrate (index 4). The requirements are: The two coating materials are Ge and ZnS (indices 4.2 and 2.2). Although this coating could be designed by \u201cbrute force\u201d (just input the optimization targets and let needle\/tunneling&#8230;<\/p>\n","protected":false},"author":15,"featured_media":0,"parent":258,"menu_order":28,"comment_status":"closed","ping_status":"closed","template":"liquid.php","meta":{"footnotes":""},"tags":[],"class_list":["post-341","page","type-page","status-publish","hentry"],"_links":{"self":[{"href":"https:\/\/www.hulinks.co.jp\/en\/wp-json\/wp\/v2\/pages\/341","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.hulinks.co.jp\/en\/wp-json\/wp\/v2\/pages"}],"about":[{"href":"https:\/\/www.hulinks.co.jp\/en\/wp-json\/wp\/v2\/types\/page"}],"author":[{"embeddable":true,"href":"https:\/\/www.hulinks.co.jp\/en\/wp-json\/wp\/v2\/users\/15"}],"replies":[{"embeddable":true,"href":"https:\/\/www.hulinks.co.jp\/en\/wp-json\/wp\/v2\/comments?post=341"}],"version-history":[{"count":4,"href":"https:\/\/www.hulinks.co.jp\/en\/wp-json\/wp\/v2\/pages\/341\/revisions"}],"predecessor-version":[{"id":690,"href":"https:\/\/www.hulinks.co.jp\/en\/wp-json\/wp\/v2\/pages\/341\/revisions\/690"}],"up":[{"embeddable":true,"href":"https:\/\/www.hulinks.co.jp\/en\/wp-json\/wp\/v2\/pages\/258"}],"wp:attachment":[{"href":"https:\/\/www.hulinks.co.jp\/en\/wp-json\/wp\/v2\/media?parent=341"}],"wp:term":[{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.hulinks.co.jp\/en\/wp-json\/wp\/v2\/tags?post=341"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}