Article Abstracts | June 2006
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Photonic Crystals Enable Single-Mode Vertical-Cavity Surface-Emitting Lasers
VCSELs would be practical in many new applications if they oscillated in a single optical mode. A novel approach to making single-mode VCSELs involves a periodic pattern of holes etched into their top facet.
by Paul O. Leisher and Dr. Kent D. Choquette, University of Illinois at Urbana-Champaign
The vertical-cavity surface-emitting laser (VCSEL) has been the subject of intense research since its development in 1977.1 The standard device structure consists of a doped, highly reflective bottom distributed Bragg reflector; an undoped, multiple-quantum-well active region; and a top distributed Bragg reflector with opposite doping. These layers typically are grown by metallorganic chemical vapor deposition. Electrodes are added to the top and bottom distributed Bragg reflectors, and either proton implantation or selective oxidation is used to provide current confinement.2
This design offers several advantages over traditional Fabry-Perot, edge-emitting semiconductor lasers, such as small size, compatibility with on-wafer testing and the fabrication of large arrays, and a round, low-divergence output beam. These features make VCSELs attractive, low-cost laser sources for many near-IR applications, including optical interconnects and gigabit local area networks...
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