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Semiconductor Lasers: Infrared to Blue Devices. Jim Guido. Origins . Semiconductor lasers have existed for about 40 years. First demonstrated by Robert N. Hall at General Electric in 1962. Motivation. Semiconductor lasers have a wide range of useful applications.
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Origins • Semiconductor lasers have existed for about 40 years. • First demonstrated by Robert N. Hall at General Electric in 1962.
Motivation • Semiconductor lasers have a wide range of useful applications. • Many architectures exist for implementing laser diodes. • Devices scale with technology.
Basic Principles Stimulated Emission • Electron distribution in a binary semiconductor (GaAs) is where N2 > N1 and E2 > E1 in order to receive the optical amplification necessary for lasing action to occur.
Basic Principles Resonant Optical Cavity • Causes an increase in optical intensity via positive feedback. • Waves propagate by reflecting back and forth between the two end mirrors. • For resonance to occur, the optical cavity must satisfy the following condition where N is an integer, and L is the length of the optical cavity. • L > λ (typically) which leads to multiple lasing modes.
Basic Applications Optical Storage Devices • CD-ROM/RW, DVD, HD-DVD, BLU-RAY I/O Devices • Bar-code readers, laser printers, scanners Telecommunications • Light sources to fiber optic networks High-energy Devices • Gem-cutting, Laser Fusion
The Future? • Indirect Bandgap Devices Why? • Devices formed from silicon can have more metal layers than their GaAs counterparts. • Silicon is cheaper, and more prevalent. • Semiconductor lasers formed from silicon might make optical interconnects more feasible.
References [1] “Laser diode.” Wikipedia. 28 Nov. 2006. Wikimedia Foundation, Inc. 16 Nov. 2006 http://en.wikipedia.org/wiki/Laser_diode [2] “Stimulated Emission.” Wikipedia. 2 Dec. 2006. Wikimedia Foundation, Inc. 15 Dec. 2006 http://en.wikipedia.org/wiki/Stimulated_Emission [3] Neamen , Donald A. Semiconductor Physics and Devices: Basic Principles. New York: McGraw-Hill, 2003, pp. 653-661. [4] Coffa, Salvatore. “Light From Silicon.” IEEE Spectrum. Oct. 2005: 44-49.