{"id":12122,"date":"2023-11-25T12:09:06","date_gmt":"2023-11-25T11:09:06","guid":{"rendered":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122"},"modified":"2023-11-25T12:17:10","modified_gmt":"2023-11-25T11:17:10","slug":"a-semiconductor-laser-for-information-read-out-cql10","status":"publish","type":"post","link":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122","title":{"rendered":"A semiconductor laser for information read-out – CQL10"},"content":{"rendered":"

A semiconductor laser for information read-out <\/i><\/strong><\/h4>\n

PTechReview-39-1980-037<\/a><\/span><\/i><\/strong><\/h4>\n

J. C. J. Finek, H. J. M. van der Laak and J. T. Schrama<\/i><\/p>\n

Semiconductor lasers only became efficient lasers when they were made in theform of ‘double<\/i><\/p>\n

heteroj unctions’: an active layer in which the laser radiation is produced, between two layers of<\/i><\/p>\n

another composition. In the first lasers of this type the active layer consisted of GaAs. The laser<\/i><\/p>\n

radiation from this m\u00e0terial has a wavelength of about 890 nm. Since then the development of<\/i><\/p>\n

semiconductor lasers has moved simultaneously in two opposing directions. On the one hand<\/i><\/p>\n

there is a clear needfor laser radiation at longer wavelengthsfor optical communication by glass<\/i><\/p>\n

fibres, since Rayleigh scattering in the fibres is lower at these longer wavelengths. On the other<\/i><\/p>\n

hand there is a need for semiconductor lasers that produce radiation at shorter wavelengths for<\/i><\/p>\n

applications in which the radiated power is concentrated in the smallest possible area. This<\/i><\/p>\n

article describes a laserof this shorter- wavelength type that Philips isputting on the market. The<\/i><\/p>\n

wavelength of the emitted radiation is 780 nm.<\/i><\/p>\n

 <\/p>\n

Introduction<\/i><\/strong><\/p>\n

The information on a ‘VLP’ disc is recorded in a <\/i>spiral track 25 km long, with a pitch of 1.66 urn and<\/i><\/p>\n

consisting of pits 0.6 urn wide and 0.12 urn deep. This <\/i>form of information storage also has its attractions<\/i><\/p>\n

for applications such as audio discs and data filing, <\/i>mainly because it can provide a very high information<\/i><\/p>\n

density – of the order of one bit per um”, Philips are <\/i>active in the development of such systems (‘Compact<\/i><\/p>\n

Disc’; ‘DOR’ <\/i>= <\/i>Digital Optical Recording). <\/i>The information stored in this way is read out by<\/i><\/p>\n

scanning the track of pits with an optical system; a <\/i>photodiode converts the intensity variations of the reflected<\/i><\/p>\n

light into an electrical signal <\/i>(fig. 1): <\/i>The <\/i>requirements imposed on the light source <\/i>(L) <\/i>for this<\/i><\/p>\n

system can only be met by lasers: the radiation must <\/i>have a radiation density of about 2500 W per cm<\/i>2 <\/i>per<\/i><\/p>\n

steradian for a detected signal with an acceptable <\/i>signal-to-noise ratio to be generated by the variations<\/i><\/p>\n

in reflection from an area of about 1 <\/i>Ilm<\/i>2 <\/i>[11. <\/i>The <\/i>light source in the ‘VLP’ system is at present a <\/i>helium-neon laser <\/i>[21<\/i><\/p>\n

\"\"<\/p>\n","protected":false},"excerpt":{"rendered":"

A semiconductor laser for information read-out PTechReview-39-1980-037 J. C. J. Finek, H. J. M. van der Laak and J. T. Schrama Semiconductor lasers only became efficient lasers when they were made in theform of...<\/p>\n","protected":false},"author":1,"featured_media":12121,"comment_status":"closed","ping_status":"closed","sticky":false,"template":"","format":"standard","meta":{"footnotes":""},"categories":[121],"tags":[],"class_list":["post-12122","post","type-post","status-publish","format-standard","has-post-thumbnail","hentry","category-philips"],"yoast_head":"\nA semiconductor laser for information read-out - CQL10 - Bram Jacobse<\/title>\n<meta name=\"robots\" content=\"index, follow, max-snippet:-1, max-image-preview:large, max-video-preview:-1\" \/>\n<link rel=\"canonical\" href=\"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122\" \/>\n<meta property=\"og:locale\" content=\"en_US\" \/>\n<meta property=\"og:type\" content=\"article\" \/>\n<meta property=\"og:title\" content=\"A semiconductor laser for information read-out - CQL10 - Bram Jacobse\" \/>\n<meta property=\"og:description\" content=\"A semiconductor laser for information read-out PTechReview-39-1980-037 J. C. J. Finek, H. J. M. van der Laak and J. T. Schrama Semiconductor lasers only became efficient lasers when they were made in theform of...\" \/>\n<meta property=\"og:url\" content=\"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122\" \/>\n<meta property=\"og:site_name\" content=\"Bram Jacobse\" \/>\n<meta property=\"article:published_time\" content=\"2023-11-25T11:09:06+00:00\" \/>\n<meta property=\"article:modified_time\" content=\"2023-11-25T11:17:10+00:00\" \/>\n<meta property=\"og:image\" content=\"https:\/\/www.bramjacobse.nl\/wordpress\/wp-content\/uploads\/2023\/11\/CQL10_Laser.jpg\" \/>\n\t<meta property=\"og:image:width\" content=\"1280\" \/>\n\t<meta property=\"og:image:height\" content=\"701\" \/>\n\t<meta property=\"og:image:type\" content=\"image\/jpeg\" \/>\n<meta name=\"author\" content=\"Bram\" \/>\n<meta name=\"twitter:card\" content=\"summary_large_image\" \/>\n<meta name=\"twitter:label1\" content=\"Written by\" \/>\n\t<meta name=\"twitter:data1\" content=\"Bram\" \/>\n\t<meta name=\"twitter:label2\" content=\"Est. reading time\" \/>\n\t<meta name=\"twitter:data2\" content=\"2 minutes\" \/>\n<script type=\"application\/ld+json\" class=\"yoast-schema-graph\">{\"@context\":\"https:\\\/\\\/schema.org\",\"@graph\":[{\"@type\":\"Article\",\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122#article\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122\"},\"author\":{\"name\":\"Bram\",\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/#\\\/schema\\\/person\\\/046607e546e3a7190b34f7793abbe6fe\"},\"headline\":\"A semiconductor laser for information read-out – CQL10\",\"datePublished\":\"2023-11-25T11:09:06+00:00\",\"dateModified\":\"2023-11-25T11:17:10+00:00\",\"mainEntityOfPage\":{\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122\"},\"wordCount\":371,\"publisher\":{\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/#\\\/schema\\\/person\\\/046607e546e3a7190b34f7793abbe6fe\"},\"image\":{\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/wp-content\\\/uploads\\\/2023\\\/11\\\/CQL10_Laser.jpg\",\"articleSection\":[\"Philips\"],\"inLanguage\":\"en-US\"},{\"@type\":\"WebPage\",\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122\",\"url\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122\",\"name\":\"A semiconductor laser for information read-out - CQL10 - Bram Jacobse\",\"isPartOf\":{\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/#website\"},\"primaryImageOfPage\":{\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122#primaryimage\"},\"image\":{\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122#primaryimage\"},\"thumbnailUrl\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/wp-content\\\/uploads\\\/2023\\\/11\\\/CQL10_Laser.jpg\",\"datePublished\":\"2023-11-25T11:09:06+00:00\",\"dateModified\":\"2023-11-25T11:17:10+00:00\",\"breadcrumb\":{\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122#breadcrumb\"},\"inLanguage\":\"en-US\",\"potentialAction\":[{\"@type\":\"ReadAction\",\"target\":[\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122\"]}]},{\"@type\":\"ImageObject\",\"inLanguage\":\"en-US\",\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122#primaryimage\",\"url\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/wp-content\\\/uploads\\\/2023\\\/11\\\/CQL10_Laser.jpg\",\"contentUrl\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/wp-content\\\/uploads\\\/2023\\\/11\\\/CQL10_Laser.jpg\",\"width\":1280,\"height\":701},{\"@type\":\"BreadcrumbList\",\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?p=12122#breadcrumb\",\"itemListElement\":[{\"@type\":\"ListItem\",\"position\":1,\"name\":\"Home\",\"item\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\"},{\"@type\":\"ListItem\",\"position\":2,\"name\":\"A semiconductor laser for information read-out – CQL10\"}]},{\"@type\":\"WebSite\",\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/#website\",\"url\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/\",\"name\":\"Bram Jacobse : Tinkering CD Players & Digital Audio\",\"description\":\"Tinkering CD Players & Digital Audio\",\"publisher\":{\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/#\\\/schema\\\/person\\\/046607e546e3a7190b34f7793abbe6fe\"},\"alternateName\":\"Bram Jacobse : Tinkering CD Players & Digital Audio\",\"potentialAction\":[{\"@type\":\"SearchAction\",\"target\":{\"@type\":\"EntryPoint\",\"urlTemplate\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?s={search_term_string}\"},\"query-input\":{\"@type\":\"PropertyValueSpecification\",\"valueRequired\":true,\"valueName\":\"search_term_string\"}}],\"inLanguage\":\"en-US\"},{\"@type\":[\"Person\",\"Organization\"],\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/#\\\/schema\\\/person\\\/046607e546e3a7190b34f7793abbe6fe\",\"name\":\"Bram\",\"logo\":{\"@id\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/#\\\/schema\\\/person\\\/image\\\/\"},\"url\":\"https:\\\/\\\/www.bramjacobse.nl\\\/wordpress\\\/?author=1\"}]}<\/script>\n<!-- \/ Yoast SEO plugin. -->","yoast_head_json":{"title":"A semiconductor laser for information read-out - CQL10 - Bram Jacobse","robots":{"index":"index","follow":"follow","max-snippet":"max-snippet:-1","max-image-preview":"max-image-preview:large","max-video-preview":"max-video-preview:-1"},"canonical":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122","og_locale":"en_US","og_type":"article","og_title":"A semiconductor laser for information read-out - CQL10 - Bram Jacobse","og_description":"A semiconductor laser for information read-out PTechReview-39-1980-037 J. C. J. Finek, H. J. M. van der Laak and J. T. Schrama Semiconductor lasers only became efficient lasers when they were made in theform of...","og_url":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122","og_site_name":"Bram Jacobse","article_published_time":"2023-11-25T11:09:06+00:00","article_modified_time":"2023-11-25T11:17:10+00:00","og_image":[{"width":1280,"height":701,"url":"https:\/\/www.bramjacobse.nl\/wordpress\/wp-content\/uploads\/2023\/11\/CQL10_Laser.jpg","type":"image\/jpeg"}],"author":"Bram","twitter_card":"summary_large_image","twitter_misc":{"Written by":"Bram","Est. reading time":"2 minutes"},"schema":{"@context":"https:\/\/schema.org","@graph":[{"@type":"Article","@id":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122#article","isPartOf":{"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122"},"author":{"name":"Bram","@id":"https:\/\/www.bramjacobse.nl\/wordpress\/#\/schema\/person\/046607e546e3a7190b34f7793abbe6fe"},"headline":"A semiconductor laser for information read-out – CQL10","datePublished":"2023-11-25T11:09:06+00:00","dateModified":"2023-11-25T11:17:10+00:00","mainEntityOfPage":{"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122"},"wordCount":371,"publisher":{"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/#\/schema\/person\/046607e546e3a7190b34f7793abbe6fe"},"image":{"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122#primaryimage"},"thumbnailUrl":"https:\/\/www.bramjacobse.nl\/wordpress\/wp-content\/uploads\/2023\/11\/CQL10_Laser.jpg","articleSection":["Philips"],"inLanguage":"en-US"},{"@type":"WebPage","@id":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122","url":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122","name":"A semiconductor laser for information read-out - CQL10 - Bram Jacobse","isPartOf":{"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/#website"},"primaryImageOfPage":{"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122#primaryimage"},"image":{"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122#primaryimage"},"thumbnailUrl":"https:\/\/www.bramjacobse.nl\/wordpress\/wp-content\/uploads\/2023\/11\/CQL10_Laser.jpg","datePublished":"2023-11-25T11:09:06+00:00","dateModified":"2023-11-25T11:17:10+00:00","breadcrumb":{"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122#breadcrumb"},"inLanguage":"en-US","potentialAction":[{"@type":"ReadAction","target":["https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122"]}]},{"@type":"ImageObject","inLanguage":"en-US","@id":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122#primaryimage","url":"https:\/\/www.bramjacobse.nl\/wordpress\/wp-content\/uploads\/2023\/11\/CQL10_Laser.jpg","contentUrl":"https:\/\/www.bramjacobse.nl\/wordpress\/wp-content\/uploads\/2023\/11\/CQL10_Laser.jpg","width":1280,"height":701},{"@type":"BreadcrumbList","@id":"https:\/\/www.bramjacobse.nl\/wordpress\/?p=12122#breadcrumb","itemListElement":[{"@type":"ListItem","position":1,"name":"Home","item":"https:\/\/www.bramjacobse.nl\/wordpress"},{"@type":"ListItem","position":2,"name":"A semiconductor laser for information read-out – CQL10"}]},{"@type":"WebSite","@id":"https:\/\/www.bramjacobse.nl\/wordpress\/#website","url":"https:\/\/www.bramjacobse.nl\/wordpress\/","name":"Bram Jacobse : Tinkering CD Players & Digital Audio","description":"Tinkering CD Players & Digital Audio","publisher":{"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/#\/schema\/person\/046607e546e3a7190b34f7793abbe6fe"},"alternateName":"Bram Jacobse : Tinkering CD Players & Digital Audio","potentialAction":[{"@type":"SearchAction","target":{"@type":"EntryPoint","urlTemplate":"https:\/\/www.bramjacobse.nl\/wordpress\/?s={search_term_string}"},"query-input":{"@type":"PropertyValueSpecification","valueRequired":true,"valueName":"search_term_string"}}],"inLanguage":"en-US"},{"@type":["Person","Organization"],"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/#\/schema\/person\/046607e546e3a7190b34f7793abbe6fe","name":"Bram","logo":{"@id":"https:\/\/www.bramjacobse.nl\/wordpress\/#\/schema\/person\/image\/"},"url":"https:\/\/www.bramjacobse.nl\/wordpress\/?author=1"}]}},"_links":{"self":[{"href":"https:\/\/www.bramjacobse.nl\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/12122","targetHints":{"allow":["GET"]}}],"collection":[{"href":"https:\/\/www.bramjacobse.nl\/wordpress\/index.php?rest_route=\/wp\/v2\/posts"}],"about":[{"href":"https:\/\/www.bramjacobse.nl\/wordpress\/index.php?rest_route=\/wp\/v2\/types\/post"}],"author":[{"embeddable":true,"href":"https:\/\/www.bramjacobse.nl\/wordpress\/index.php?rest_route=\/wp\/v2\/users\/1"}],"replies":[{"embeddable":true,"href":"https:\/\/www.bramjacobse.nl\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcomments&post=12122"}],"version-history":[{"count":0,"href":"https:\/\/www.bramjacobse.nl\/wordpress\/index.php?rest_route=\/wp\/v2\/posts\/12122\/revisions"}],"wp:featuredmedia":[{"embeddable":true,"href":"https:\/\/www.bramjacobse.nl\/wordpress\/index.php?rest_route=\/wp\/v2\/media\/12121"}],"wp:attachment":[{"href":"https:\/\/www.bramjacobse.nl\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fmedia&parent=12122"}],"wp:term":[{"taxonomy":"category","embeddable":true,"href":"https:\/\/www.bramjacobse.nl\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Fcategories&post=12122"},{"taxonomy":"post_tag","embeddable":true,"href":"https:\/\/www.bramjacobse.nl\/wordpress\/index.php?rest_route=%2Fwp%2Fv2%2Ftags&post=12122"}],"curies":[{"name":"wp","href":"https:\/\/api.w.org\/{rel}","templated":true}]}}