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. Many architectures exist for implementing laser diodes. Devices scale with technology.

Basic Principles Stimulated Emission Electron distribution in a binary semiconductor (GaAs) is where N 2 > N 1 and E 2 > E 1 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 Wikimedia Foundation, Inc. 16 Nov [2] “Stimulated Emission.” Wikipedia. 2 Dec Wikimedia Foundation, Inc. 15 Dec [3] Neamen, Donald A. Semiconductor Physics and Devices: Basic Principles. New York: McGraw-Hill, 2003, pp [4] Coffa, Salvatore. “Light From Silicon.” IEEE Spectrum. Oct. 2005: