Beschreibung
The teraÂhertz (THz) ranÂge refers to freÂquenÂciÂes betÂween 0.1 and 10 THz and represÂents the specÂtral gap betÂween the microÂwaÂve and infraÂred regiÂon. Over the past few years, theÂre has been a signiÂfiÂcant inteÂrest in employÂing THz techÂnoÂloÂgy in specÂtroÂscopy, imaÂging, and recentÂly in short-ranÂge indoor comÂmuÂniÂcaÂtiÂon sysÂtems. THz radiaÂtiÂon can be geneÂraÂted by difÂfeÂrent scheÂmes. Among them are the Far-InfraÂred (FIR) lasers which are preÂferÂred for their wide ranÂge of posÂsiÂble outÂput freÂquenÂciÂes and their high conÂtiÂnuous-wave outÂput power. In this theÂsis a FIR laser is preÂsenÂted and its working mechaÂnism is descriÂbed in detail. THz waves are able to peneÂtraÂte most non-metalÂlic objects and pose no health risk for human beinÂgs as they do not have any ioniÂzing proÂperÂties unliÂke for exampÂle X‑rays. This makes THz radiaÂtiÂon ideÂal for imaÂging appÂliÂcaÂtiÂons. An effecÂtiÂve techÂniÂque for imaÂging of small objects in thick samÂples is the so-calÂled conÂfoÂcal microÂscopy. In this work we transÂfer the principÂle of optiÂcal conÂfoÂcal microÂscopy to the THz ranÂge using a FIR laser source. DetecÂtion of THz radiaÂtiÂon represÂents one of the major hurdÂles which impeÂde the comÂmerÂcial use of a pracÂtiÂcal and cost-effecÂtiÂve THz sysÂtem. Here some exisÂting and new FIR laser detecÂtors are preÂsenÂted and their working mechaÂnism are disÂcusÂsed.