November 2012

Fabricating Nanowire Lasers

Precise control of nanowire geometry and optical environment enables tuning of lasing properties.

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Image courtesy of Sandia National Laboratories

Array of gallium nitride (GaN) nanowires fabricated by Sandia-developed top-down method. Right: Single GaN nanowire (top), sub-threshold UV emission from nanowire (middle), above-threshold UV lasing from nanowire end facets (bottom).

The Science

Single-frequency rather than the more typically-observed multiple-frequency laser output is induced in gallium nitride (GaN) nanowires by precisely controlling the geometry of the nanowire.

The Impact

Single-frequency nanowire lasers based on gallium nitride (GaN) could enable ultracompact, low-power, and low-noise coherent light sources for a variety of applications including optoelectronic circuits and microdevices, and information storage, with reduced cost and improved function.

Summary

Gallium nitride (GaN) based nanowire lasers have potential to become ultra-compact, low-power, coherent ultraviolet and visible light sources, allowing these lasers to serve in a variety of applications including writing information at high densities onto microscale media storage devices. Yet, poor optical beam and spectral properties have hampered uses of these lasers. Many potential applications require operation of the laser at a single frequency, with low noise and an optimal spatial profile. GaN lasers, however, typically produce multiple frequencies simultaneously, meaning the laser emits light in multiple, tightly-spaced, wavelengths that often travel in different directions or spatial patterns and result in beam spread and poor focusing properties. Now, researchers at Sandia National Laboratories’ Solid-State Lighting Science EFRC achieved single-frequency laser output from GaN nanowires using a new method to fabricate high quality arrays of GaN nanowires with precisely controlled geometries. The top-down fabrication technique starts from a silicon-doped GaN layer, followed by tunable dry etch plus anisotropic wet etch for precise control of the nanowire dimensions. The researchers discovered several approaches to convert multiple-frequency nanowire lasers into single-frequency lasers by controlling nanowire size, producing a coupled nanowire cavity, or by placing the nanowires onto a gold substrate.

Contact

George T. Wang
Sandia National Laboratories
gtwang@sandia.gov; www.sandia.gov/~gtwangExternal link

Michael E. Coltrin
Director, Solid-State Lighting Science (SSLS) EFRC
mecoltr@sandia.gov

Funding

DOE Office of Science, Basic Energy Sciences program, Energy Frontier Research Centers (EFRC) program.

Publications

Li, Q., J. B. Wright, W. W. Chow, T. S. Luk, I. Brener, L. F. Lester, G. T. Wang, “Single-mode GaN nanowire lasers,” Optics Express, 20, 17873 (2012). [DOI: 10.1364/OE.20.017873External link]

Xu, H., J. B. Wright, L. Ting-Shan, J. J. Figiel, K. Cross, L. F. Lester, G. Balakrishnan, G. T. Wang, I. Brener, L. Qiming, "Single-mode lasing of GaN nanowire-pairs," Appl. Phys. Lett., 101, 113106 (2012) [DOI: 10.1063/1.4751862External link]

Xu, H., J. B. Wright, A. Hurtado, Q. Li, T-S. Luk, J. J. Figiel, K. Cross, G. Balakrishnan, L. F. Lester, I. Brener, G.T. Wang, "Gold substrate-induced single-mode lasing of GaN nanowires," 2012. Appl. Phys. Lett., 101, 113106 (2012) [DOI: 10.1063/1.4768300External link]

Related Links

Solid-State Lighting Science EFRC

Highlight Categories

Program: BES, EFRCs

Performer/Facility: DOE Laboratory

Last modified: 12/6/2013 1:26:23 PM