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 materials—plastic, clothing, paper and some biological tissues—making 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 light—just 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

News and information

Feynman Prize Winners Announced! April 26th, 2015

New ASTM Standards Will Help Educate Present and Future Nanotechnology Workforces April 26th, 2015

Heat makes electrons’ spin in magnetic superconductors April 26th, 2015

QD Vision Wins 2015 Bronze Edison Award for Color IQ™ Quantum Dot Technology April 26th, 2015

Laboratories

ORNL reports method that takes quantum sensing to new level April 23rd, 2015

Scientists Use Nanoscale Building Blocks and DNA 'Glue' to Shape 3D Superlattices: New approach to designing ordered composite materials for possible energy applications April 23rd, 2015

Drexel materials scientists putting a new spin on computing memory April 22nd, 2015

Phonons, arise! Small electric voltage alters conductivity in key materials April 22nd, 2015

Govt.-Legislation/Regulation/Funding/Policy

SEFCU, SUNY Poly CNSE Announce Winning Student-Led Teams in the 6th Annual $500,000 New York Business Plan Competition April 25th, 2015

Northwestern scientists develop first liquid nanolaser: Technology could lead to new way of doing 'lab on a chip' medical diagnostics April 25th, 2015

ORNL reports method that takes quantum sensing to new level April 23rd, 2015

Electron spin brings order to high entropy alloys April 23rd, 2015

Nanotubes/Buckyballs/Fullerenes

SouthWest NanoTechnologies CEO Dave Arthur to Speak at NanoBCA DC Roundtable on May 19 in Washington DC April 20th, 2015

How to maximize the superconducting critical temperature in a molecular superconductor: International team led by Tohoku University opens new route for discovering high Tc superconductors April 19th, 2015

Nanotubes with two walls have singular qualities: Rice University lab calculates unique electronic qualities of double-walled carbon nanotubes April 16th, 2015

MIT sensor detects spoiled meat: Tiny device could be incorporated into 'smart packaging' to improve food safety April 15th, 2015

Discoveries

Heat makes electrons’ spin in magnetic superconductors April 26th, 2015

SEFCU, SUNY Poly CNSE Announce Winning Student-Led Teams in the 6th Annual $500,000 New York Business Plan Competition April 25th, 2015

Northwestern scientists develop first liquid nanolaser: Technology could lead to new way of doing 'lab on a chip' medical diagnostics April 25th, 2015

Fast and accurate 3-D imaging technique to track optically trapped particles April 24th, 2015

Announcements

Feynman Prize Winners Announced! April 26th, 2015

New ASTM Standards Will Help Educate Present and Future Nanotechnology Workforces April 26th, 2015

Heat makes electrons’ spin in magnetic superconductors April 26th, 2015

QD Vision Wins 2015 Bronze Edison Award for Color IQ™ Quantum Dot Technology April 26th, 2015

Homeland Security

UCLA nanoscientists are first to model atomic structures of three bacterial nanomachines: Cryo electron microscope enables scientists to explore the frontiers of targeted antibiotics April 21st, 2015

Optics, nanotechnology combined to create low-cost sensor for gases April 3rd, 2015

The Universitat Politècnica de València is coordinating a European project to develop a device for the quick and early diagnosis of cancer March 7th, 2015

Detecting chemical weapons with a color-changing film January 28th, 2015

Military

Electron spin brings order to high entropy alloys April 23rd, 2015

Engineer improves rechargeable batteries with MoS2 nano 'sandwich' April 18th, 2015

Cobalt film a clean-fuel find: Rice University discovery is efficient, robust at drawing hydrogen and oxygen from water April 15th, 2015

MIT sensor detects spoiled meat: Tiny device could be incorporated into 'smart packaging' to improve food safety April 15th, 2015

Photonics/Optics/Lasers

Northwestern scientists develop first liquid nanolaser: Technology could lead to new way of doing 'lab on a chip' medical diagnostics April 25th, 2015

Fast and accurate 3-D imaging technique to track optically trapped particles April 24th, 2015

ORNL reports method that takes quantum sensing to new level April 23rd, 2015

Quantum 'paparazzi' film photons in the act of pairing up April 22nd, 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