THE WHATIS.COM WORD-OF-THE-DAY March 4, 2002 vertical cavity surface emitting laser ______________ TODAY'S SPONSOR: VeriSign - The Value of Trust
FREE E-COMMERCE SECURITY GUIDE Is your e-business built on a strong, secure foundation? Find out with VeriSign's FREE White Paper, "Building an E-Commerce Trust Infrastructure." Learn how to authenticate your site to customers, secure your web servers with 128-Bit SSL encryption, and accept secure payments online. Click here: http://ad.doubleclick.net/clk;3972024;5058249;l?http://www.verisign.com/cgi-bin/go.cgi?a=n116973230057000 ______________ TODAY'S WORD: vertical cavity surface emitting laser See our definition with hyperlinks at http://whatis.techtarget.com/definition/0,,sid9_gci803517,00.html A vertical cavity surface emitting laser (VCSEL) is a specialized laser diode that promises to revolutionize fiber optic communications by improving efficiency and increasing data speed. The acronym VCSEL is pronounced 'vixel.' Older laser diodes, called edge-emitting diodes, emit coherent light or infrared (IR) energy parallel to the boundaries between the semiconductor layers. The VCSEL emits its coherent energy perpendicular to the boundaries between the layers. The vertical in VCSEL arises from the fact that laser diodes are typically diagrammed showing the boundaries as horizontal planes, so the output of the VCSEL appears to emerge vertically in these drawings. VCSELs have been constructed that emit energy at 850 nanometers (nm) and 1300 nm. These wavelengths correspond to energy in the near infrared (IR) portion of the electromagnetic spectrum. (The longest visible red is at approximately 770 nm.) Optical fibers transmit energy most efficiently at wavelengths around 1550 nm. Materials used to manufacture VCSELs include gallium arsenide (GaAs), aluminum gallium arsenide (AlGaAs), and indium gallium arsenide nitride (InGaAsN). The VCSEL has several advantages over edge-emitting diodes. The VCSEL is cheaper to manufacture in quantity, is easier to test, and is more efficient. In addition, the VCSEL requires less electrical current to produce a given coherent energy output. The VCSEL emits a narrow, more nearly circular beam than traditional edge emitters; this makes it easier to get the energy from the device into an optical fiber. The main challenge facing engineers today is the development of a high-power VCSEL device with an emission wavelength of 1550 nm. RELATED TERMS: laser http://whatis.techtarget.com/definition/0,,sid9_gci214527,00.html diode http://whatis.techtarget.com/definition/0,,sid9_gci213519,00.html laser diode http://whatis.techtarget.com/definition/0,,sid9_gci213532,00.html fiber optic http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci212113,00.html infrared http://searchnetworking.techtarget.com/sDefinition/0,,sid7_gci214039,00.html semiconductor http://whatis.techtarget.com/definition/0,,sid9_gci212960,00.html nanometer http://whatis.techtarget.com/definition/0,,sid9_gci514407,00.html ______________________ SELECTED LINKS: Sandia National Laboratories pioneered the gallium arsenide VCSEL. http://www.sandia.gov/media/NewsRel/NR2000/laser.htm Infineon Technologies has a VCSEL with 1300 nm output. http://www.compoundsemiconductor.net/PressReleases/2001/PR04050101.htm ______________________ QUIZ #21 | Last chance at the zoo quiz! We're quite sure you know what a mouse is. But what do you know about the packet monkey? Are you familiar with the infamous dogcow? We have left up one of our most difficult quizzes (a mixed-bag of IT terms that sound like animal names) for those readers who may have missed it. Good luck! http://whatis.techtarget.com/definition/0,,sid9_gci796012,00.html _________________________ FREE STORAGE MANAGEMENT CONFERENCE Time's running out to attend Storage Management March 20-22 at the Hilton Chicago Hotel. 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