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2004 SCIENCE NEWS
01.06.04 - Understanding the Lasing Mechanism of a Nanolaser
Nanolasers are tiny semiconductor lasers with dimensions of only tens of nanometers. Nanolasers have excellent potential applications in future nano-photonic systems, chip-scale photonic integrated circuits, and other optical interconnects and light sources. However, the operating mechanisms of these devices are not yet understood. Scientists Alex Maslov and Cun-Zheng Ning (NAS) have made significant progress toward understanding the lasing mechanism of a nanolaser. Maslov and Ning performed a computer simulation of optical modes in a semiconductor nanowire of tens of nanometers in diameter. Their simulation showed interesting modal properties and reflection of strongly confined modes in a nanowire. The results were published in Applied Physics Letters and also included in the "Optics in 2003", a year end issue of Optics and Photonics News Magazine published by the Optical Society of America.
A nanolaser is made of semiconductor nanowire, which has a diameter of only tens of nanometers and a length of a few microns-the smallest laser ever made. Just two years ago, groups at Berkeley and Harvard demonstrated a working nanolaser for the first time. However, the mechanism of lasing in these nanolasers is still not known. Even though detailed experimental characterization is required and underway, NASA Ames scientists Maslov and Ning decided that theoretical modeling and computer simulation could shed light on the lasing mechanism.
One of the first tasks was to determine the nature and type of optical modes that could be supported in such a nanowire with a diameter much smaller than the wavelength of light. To investigate this, the team performed a simulation of optical modes based on a finite-difference time-domain method. They were able to calculate the reflection coefficients of guided modes at the nanowire facets. Such information is critical for determining the modal properties and the minimum amount of external pumping for achieving lasing operation.
The results of this investigation were published in Applied Physics Letters (Vol. 83, 1237(2003) and included in the "Optics in 2003", a year end issue of Optics and Photonics News Magazine (December Issue) published by the Optical Society of America. This research is part of the effort under a Director's Discretionary Fund project on nanolasers. The researchers are now conducting further investigations toward a full understanding of the lasing mechanism.
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