Editing Laser diode (section)

== Applications ==
[[file:Laser diode array.jpg|thumb|right|250px|Laser diodes can be arrayed to produce very high power outputs, continuous-wave or pulsed. Such arrays may be used to efficiently pump solid-state lasers for high-average-power drilling or burning and for [[inertial confinement fusion]].]]

Laser diodes are numerically the most common laser type, with 2004 sales of approximately 733 million units,<ref>{{cite journal |last = Steele |first = Robert V. |year = 2005 |title = Diode-laser market grows at a slower rate |journal = Laser Focus World |volume = 41 |issue = 2 |url = https://lfw.pennnet.com/Articles/Article_Display.cfm?Section=ARCHI&ARTICLE_ID=221439&VERSION_NUM=4&p=12 |archive-url = https://web.archive.org/web/20060408222140/http://lfw.pennnet.com/Articles/Article_Display.cfm?Section=ARCHI&ARTICLE_ID=221439&VERSION_NUM=4&p=12 |url-status = dead |archive-date = 2006-04-08 }}</ref> as compared to 131,000 of other types of lasers.<ref>{{cite journal|last=Kincade |first=Kathy |author2=Anderson, Stephen |year=2005 |title=Laser Marketplace 2005: Consumer applications boost laser sales 10% |journal=Laser Focus World |volume=41 |issue=1 |url=http://lfw.pennnet.com/Articles/Article_Display.cfm?section=ARCHI&ARTICLE_ID=219847&VERSION_NUM=2&p=12 |url-status=dead |archive-url=https://web.archive.org/web/20060628041143/http://lfw.pennnet.com/Articles/Article_Display.cfm?Section=ARCHI&ARTICLE_ID=219847&VERSION_NUM=2&p=12 |archive-date=June 28, 2006 }}</ref>

=== Telecommunications, scanning, and spectrometry ===
Laser diodes are widely used in [[telecommunications]] as easily modulated and easily coupled light sources for [[optical fiber|fiber-optic]] communication. They are used in various measuring instruments, such as [[rangefinding telemeter|rangefinders]]. Another common use is in [[barcode reader]]s. [[visible spectrum|Visible]] lasers, typically [[red]] but later also [[green]], are common as [[laser pointer]]s. 

Both low- and high-power diodes are used extensively in the printing industry, both as light sources for scanning (input) of images and for very-high-speed and high-resolution printing plate (output) manufacturing. 

[[Infrared]] and red laser diodes are common in [[compact disc player|CD players]], [[CD-ROM]]s, and [[DVD]] technology. [[violet (color)|Violet]] lasers are used in [[HD DVD]] and [[Blu-ray Disc|Blu-ray]] technology. Diode lasers have also found many applications in [[laser absorption spectrometry]] (LAS) for high-speed, low-cost assessment or monitoring of the concentration of various species in gas phase. 

High-power laser diodes are used in industrial applications such as heat treating, cladding, seam welding, and for pumping other lasers, such as [[diode-pumped solid-state laser]]s.

Uses of laser diodes can be categorized in various ways. Most applications could be served by larger solid-state lasers or optical parametric oscillators, but the low cost of mass-produced diode lasers makes them essential for mass-market applications. Diode lasers can be used in a great many fields; since light has many different properties (power, wavelength, spectral and beam quality, polarization, etc.), it is useful to classify applications by these basic properties.

Many applications of diode lasers primarily make use of the ''directed energy'' property of the optical beam. In this category, one might include

* [[laser printer]]s
* [[Barcode reader|barcode readers]]
* [[image scanning]]
* illuminators
* designators
* [[Optical disc|optical data recording]]
* [[laser ignition|combustion ignition]]
* [[laser surgery]] - laser used to cut the tissue
* industrial [optical] sorting
* industrial machining
* [[wireless power transfer]], as power beaming
* [[directed energy weaponry]]

Some of the above applications are well-established, while others are emerging.

=== Medical uses ===
[[Laser medicine]]: medicine and especially dentistry have found many new uses for diode lasers.<ref>{{cite journal|pmid=16366049|year=2005|title=Using a diode laser to uncover dental implants in second-stage surgery|volume=53|issue=6|pages=414–7|journal=General Dentistry|last1=Yeh|first1=S|last2=Jain|first2=K|last3=Andreana|first3=S}}</ref><ref>{{cite journal|pmid=16358809|year=2005|title=The use of diode lasers in periodontal therapy: literature review and suggested technique|volume=24|issue=11|pages=130, 132–5|journal=Dentistry Today|last1=Andreana|first1=S}}</ref><ref>{{cite journal |vauthors=Borzabadi-Farahani A|title=The Adjunctive Soft-Tissue Diode Laser in Orthodontics|journal=Compend Contin Educ Dent.|volume=37|pages=e18–e31 |issue=eBook 5 |date= 2017 | pmid=28509563}}</ref><ref>{{cite journal|author=Borzabadi-Farahani, A. |title=A Scoping Review of the Efficacy of Diode Lasers Used for Minimally Invasive Exposure of Impacted Teeth or Teeth with Delayed Eruption |journal=Photonics |date=2022 |doi=10.3390/photonics9040265 |volume=9 |issue=4|page=265 |bibcode=2022Photo...9..265B |doi-access=free }}</ref><ref>{{cite journal|doi=10.1007/s10103-007-0440-3|title=Laser applications in oral surgery and implant dentistry|year=2007|last1=Deppe|first1=Herbert|first2=Hans-Henning|journal=Lasers in Medical Science|volume=22|pages=217–221|pmid=17268764|last2=Horch|issue=4|s2cid=23606690|url=http://mediatum.ub.tum.de/doc/675510/document.pdf}}{{Dead link|date=November 2018 |bot=InternetArchiveBot |fix-attempted=yes }}</ref><ref>{{cite book |last=Borzabadi-Farahani |first=A| editor-last1=Coluzzi |editor-first1=D.J. |editor-last2=Parker |editor-first2=S.P.A.| title=Lasers in Dentistry—Current Concepts. Textbooks in Contemporary Dentistry |publisher=Springer, Cham |date=2024 |edition=2nd |pages=379–398 |chapter=Laser Use in Muco-Gingival Surgical Orthodontics |isbn=978-3-031-43338-2 | doi=10.1007/978-3-031-43338-2}}</ref> The shrinking size and cost<ref>{{Cite web|url=http://www.dentaleconomics.com/articles/print/volume-101/issue-5/technology-needs/cuts-like-a-knife.html|title=Cuts Like A Knife|last=Feuerstein|first=Paul|website=Dental Economics|date=May 2011 |access-date=2016-04-12}}</ref> of the units and their increasing user-friendliness makes them very attractive to clinicians for minor soft-tissue procedures. 

Diode wavelengths range from 810 to 1,100 [[Nanometre|nm]], are poorly absorbed by soft tissue, and are not used for cutting or [[ablation]].<ref>{{Cite book|url=https://archive.org/details/lasersurgeryingy0000wrig|url-access=registration|title=Laser Surgery in Gynecology: A Clinical Guide|last1=Wright|first1=V. Cecil|last2=Fisher|first2=John C.|date=1993-01-01|publisher=Saunders|isbn=9780721640075|pages=[https://archive.org/details/lasersurgeryingy0000wrig/page/58 58]–81|language=en}}</ref><ref>{{Cite book|url=https://books.google.com/books?id=ySwYpTFZshgC|title=Endoscopic Laser Surgery Handbook|last=Shapshay|first=S. M.|date=1987-06-16|publisher=CRC Press|isbn=9780824777111|pages=1–130|language=en}}</ref><ref name=":0">{{Cite journal|last=Romanos|first=Georgios E.|date=2013-12-01|title=Diode laser soft-tissue surgery: advancements aimed at consistent cutting, improved clinical outcomes|journal=Compendium of Continuing Education in Dentistry|volume=34|issue=10|pages=752–7; quiz 758|pmid=24571504}}</ref><ref name=":1">{{Cite journal|last=Vitruk|first=PP|date=2015|title=Oral Soft Tissue Laser Ablative and Coagulative Efficiencies Spectra|url=https://lightscalpel.com/publications/oral-soft-tissue-laser-ablative-and-coagulative-efficiencies-spectra/|journal=Implant Practice US|volume=7|issue=6|pages=19–27}}</ref> Soft tissue is not cut by the laser's beam, but is instead cut by contact with a hot charred glass tip.<ref name=":0" /><ref name=":1" /> The laser's irradiation is highly absorbed at the distal end of the tip and heats it up to 500–900°C.<ref name=":0" /> Because the tip is so hot, it can be used to cut soft tissue and can cause [[hemostasis]] through [[cauterization]] and [[carbonization]].<ref name=":0" /><ref name=":1" /> Diode lasers when used on soft tissue can cause extensive collateral thermal damage to surrounding tissue.<ref name=":0" /><ref name=":1" />

As laser beam light is inherently [[coherence (physics)|coherent]], certain applications use the coherence of laser diodes. These include interferometric distance measurement, [[holography]], coherent communications, and coherent control of chemical reactions.

Laser diodes are used for their narrow spectral properties in the areas of range-finding, telecommunications, infra-red countermeasures, [[Tunable Diode Laser Absorption Spectrometry|spectroscopic sensing]], generation of radio-frequency or terahertz waves, atomic clock state preparation, quantum key cryptography, frequency doubling and conversion, water purification (in the UV), and photodynamic therapy (where a particular wavelength of light would cause a substance such as [[porphyrin]] to become chemically active as an anti-cancer agent only where the tissue is illuminated by light).

Laser diodes are used for their ability to generate ultra-short pulses of light by the technique known as ''mode-locking''. Areas of use include clock distribution for high-performance integrated circuits, high-peak-power sources for laser-induced breakdown spectroscopy sensing, arbitrary waveform generation for radio-frequency waves, photonic sampling for analog-to-digital conversion, and optical [[Code-division multiple access|code-division-multiple-access]] systems for secure communication.

=== Maskless photolithography ===
Laser diodes are used as a light source for [[maskless lithography|maskless photolithography]].