Nanotechnology Now







Heifer International

Wikipedia Affiliate Button


DHgate

Home > Press > Piece of Cake: Arrays of Long Nanotubes May Help Measure Terahertz Laser Power

"Cupcakes" of vertically aligned carbon nanotube arrays (VANTAs) grown on silicon, which appears blue in the photo. A chunk of VANTA can be sliced from the silicon with a razor blade and, using the blade as a spatula, easily moved to the top of a laser power detector. The very dark nanotube coating absorbs terahertz laser light.
Credit: Lehman/NIST
"Cupcakes" of vertically aligned carbon nanotube arrays (VANTAs) grown on silicon, which appears blue in the photo. A chunk of VANTA can be sliced from the silicon with a razor blade and, using the blade as a spatula, easily moved to the top of a laser power detector. The very dark nanotube coating absorbs terahertz laser light.

Credit: Lehman/NIST

Abstract:
Terahertz radiation can penetrate numerous materialsóplastic, clothing, paper and some biological tissuesómaking it an attractive candidate for applications such as concealed weapons detection, package inspection and imaging skin tumors. However, to date there is no standard method for measuring the absolute output power of terahertz lasers, one source of this type of radiation. Now, researchers at the National Institute of Standards and Technology (NIST) have found that dense arrays of extra-long carbon nanotubes absorb nearly all light of long wavelengths, and thus are promising coatings for prototype detectors intended to measure terahertz laser power.*

Piece of Cake: Arrays of Long Nanotubes May Help Measure Terahertz Laser Power

Boulder, CO | Posted on July 21st, 2011

The research is part of NIST's effort to develop the first U.S. reference standards** for calibrating lasers that operate in the terahertz range, from the far infrared at wavelengths of 100 micrometers to the edge of the microwave band at 1 millimeter.

"There is no measurement traceability for absolute power for terahertz laser sources," NIST project leader John Lehman says. "We have customers asking for the calibrations. This coating looks viable for terahertz laser power detectors."

The coating, called a VANTA (vertically aligned carbon nanotube array), has several desirable properties. Most obviously, it is easy to handle. The nanotubes are tens of micrometers to over a millimeter long, so a dense layer is visible without a microscope. A chunk of VANTA can be cut, lifted, and carried like a piece of cake, making it easy to transfer from a silicon surface where the tubes are grown to a laser power detector.

Most importantly, the coating is very dark. The NIST team evaluated three VANTA samples with average lengths of 40 and 150 micrometers and 1.5 millimeters (mm) and found that longer tubes reflect less light. The 1.5 mm version reflects almost no lightójust 1 percent at a wavelength of 394 micrometers. This result, the first-ever evaluation of a VANTA's reflectance at that terahertz wavelength, indicates that virtually all arriving laser light is absorbed, which would enable highly accurate measurements of laser power.

The 1.5 mm VANTA absorbs more light than comparable coatings such as gold black, but more work is needed to calculate uncertainties and determine effects of factors such as light angle. The project extends NIST's long history in laser power measurements and Lehman's recent advances in ultradark nanotube coatings.***

VANTAs also have desirable thermal properties. NIST researchers found that the material absorbs and releases heat quickly compared to other black coatings, which will make the detectors more responsive and quicker to produce signals. Otherwise, a coating thick enough to absorb long wavelengths of light would not efficiently transmit heat to the detector.

In developing the capability for terahertz laser radiometry, NIST is building a terahertz laser designed for routine measurements and a detector called a thermopile to measure the laser's power. This simple detector design produces a voltage when heat is applied to a junction of two dissimilar metals. NIST researchers used the VANTA to coat a prototype thermopile. Further research is planned to design detectors that might be used as reference standards.

* J.H. Lehman, B. Lee and E.N. Grossman. Far infrared thermal detectors for radiometry using a carbon nanotube array. Applied Optics. Posted online July 18, 2011.

** The Physikalisch-Technische Bundesanstalt (PTB), the German national metrology institute, operates a detector based measurement facility for characterization and calibration of THz-detectors at 2.52 THz. The available spectral range for detector calibration will be expanded to 1 THz to 5 THz in the future.

*** See NIST Tech Beat article "Extreme Darkness: Carbon Nanotube Forest Covers NIST's Ultra-dark Detector," August 17, 2010, at www.nist.gov/pml/optoelectronics/dark_081710.cfm.

####

About NIST
The National Institute of Standards and Technology (NIST) is an agency of the U.S. Department of Commerce.

For more information, please click here

Contacts:
Laura Ost
303-497-4880

Copyright © NIST

If you have a comment, please Contact us.

Issuers of news releases, not 7th Wave, Inc. or Nanotechnology Now, are solely responsible for the accuracy of the content.

Bookmark:
Delicious Digg Newsvine Google Yahoo Reddit Magnoliacom Furl Facebook

Related News Press

Laboratories

Nanoshuttle wear and tear: It's the mileage, not the age January 26th, 2015

News and information

Nanoparticles Increase Durability of Concrete Decorations in Cold Areas January 26th, 2015

Iranian Researchers Boost Solar Cells Efficiency Using Anti-Aggregates January 26th, 2015

Detection of Heavy Metals in Samples with Naked Eye January 26th, 2015

Engineering self-assembling amyloid fibers January 26th, 2015

Govt.-Legislation/Regulation/Funding/Policy

Nanoshuttle wear and tear: It's the mileage, not the age January 26th, 2015

Visualizing interacting electrons in a molecule: Scientists at Aalto University and the University of Zurich have succeeded in directly imaging how electrons interact within a single molecule January 26th, 2015

The latest fashion: Graphene edges can be tailor-made: Rice University theory shows it should be possible to tune material's properties January 24th, 2015

Scientists 'bend' elastic waves with new metamaterials that could have commercial applications: Materials could benefit imaging and military enhancements such as elastic cloaking January 23rd, 2015

Nanotubes/Buckyballs

Chromium-centered cycloparaphenylene rings for making functionalized nanocarbons January 26th, 2015

GS7 Graphene Sensor maybe Solution in Fight Against Cancer January 25th, 2015

Toyocolor to Launch New Carbon Nanotube Materials at nano tech 2015 January 24th, 2015

Carbon nanotube finding could lead to flexible electronics with longer battery life January 14th, 2015

Discoveries

Visualizing interacting electrons in a molecule: Scientists at Aalto University and the University of Zurich have succeeded in directly imaging how electrons interact within a single molecule January 26th, 2015

Electronic circuits with reconfigurable pathways closer to reality January 26th, 2015

Nanoparticles Increase Durability of Concrete Decorations in Cold Areas January 26th, 2015

Iranian Researchers Boost Solar Cells Efficiency Using Anti-Aggregates January 26th, 2015

Announcements

Nanoparticles Increase Durability of Concrete Decorations in Cold Areas January 26th, 2015

Iranian Researchers Boost Solar Cells Efficiency Using Anti-Aggregates January 26th, 2015

Detection of Heavy Metals in Samples with Naked Eye January 26th, 2015

Engineering self-assembling amyloid fibers January 26th, 2015

Homeland Security

Detection of Heavy Metals in Samples with Naked Eye January 26th, 2015

Detecting gases wirelessly and cheaply: New sensor can transmit information on hazardous chemicals or food spoilage to a smartphone December 8th, 2014

Laser sniffs out toxic gases from afar: System can ID chemicals in the atmosphere from a kilometer away December 4th, 2014

Better bomb-sniffing technology: University of Utah engineers develop material for better detectors November 4th, 2014

Military

Detection of Heavy Metals in Samples with Naked Eye January 26th, 2015

The latest fashion: Graphene edges can be tailor-made: Rice University theory shows it should be possible to tune material's properties January 24th, 2015

Scientists 'bend' elastic waves with new metamaterials that could have commercial applications: Materials could benefit imaging and military enhancements such as elastic cloaking January 23rd, 2015

Laser-generated surface structures create extremely water-repellent metals: Super-hydrophobic properties could lead to applications in solar panels, sanitation and as rust-free metals January 20th, 2015

Photonics/Optics/Lasers

Scientists 'bend' elastic waves with new metamaterials that could have commercial applications: Materials could benefit imaging and military enhancements such as elastic cloaking January 23rd, 2015

Teijin to Participate in Nano Tech 2015 January 22nd, 2015

New method to generate arbitrary optical pulses January 21st, 2015

New signal amplification process set to transform communications, imaging, computing: UC San Diego researchers discover a mechanism to amplify signals in optoelectronic systems that is far more efficient than standard processes January 21st, 2015

NanoNews-Digest
The latest news from around the world, FREE



  Premium Products
NanoNews-Custom
Only the news you want to read!
 Learn More
NanoTech-Transfer
University Technology Transfer & Patents
 Learn More
NanoStrategies
Full-service, expert consulting
 Learn More










ASP
Nanotechnology Now Featured Books




NNN

The Hunger Project







© Copyright 1999-2015 7th Wave, Inc. All Rights Reserved PRIVACY POLICY :: CONTACT US :: STATS :: SITE MAP :: ADVERTISE