Featured Product
This Week in Quality Digest Live
Metrology Features
Aaron Heinrich
An optimal process requires an innovative control algorithm
Harish Jose
Using OC curves to generate reliability/confidence values
Scott Knoche
Choosing the best, most appropriate add-ons makes your work faster and easier
Adam Zewe
Key component for portable mass spectrometers
Peter Büscher
Identify contaminated areas and take steps to optimize them

More Features

Metrology News
Reliable, remote visual inspections and diagnostics in hard-to-reach areas
Ideal for dusty manufacturing environments, explosive atmospheres
Optimized for cured tire runout and bulge measurement
With coupling capacitor approach that eliminates the need for an external sensor
Improving quality control of PCBAs and optimizing X-ray inspection
10-year technology partnership includes sponsorship of quality control lab
MM series features improved functionality and usability
Features improved accuracy, resolution, versatility, and efficiency

More News



Frequency Converter Enables Ultra-High Sensitivity IR Spectrometry

Highly sensitive, low-cost technique measures light in the near-infrared range.

Published: Tuesday, August 25, 2009 - 13:59

(NIST: Gaithersburg, MD) -- In what may prove to be a major development for scientists in fields ranging from forensics to quantum communications, researchers at the National Institute of Standards and Technology (NIST) have developed a new, highly sensitive, low-cost technique for measuring light in the near-infrared (NIR) range. The technique can measure the spectrum of the specific wavelengths of NIR light used widely in telecommunications as well as the very weak infrared (IR) light at single-photon levels given off by fragile biomaterials and nanomaterials. They described their results in a recent issue of Optics Express.*

A single photon detector is the key device needed to build highly sensitive instruments for measuring spectra. For the past 30 years, scientists have made steady progress increasing the efficiency and sensitivity of visible and ultraviolet photon detectors while methods for detecting elusive single photons in the NIR range have faltered. The methods presently in use are too static-laden, inefficient, and slow, or depend on superconducting detectors, which require expensive, low-temperature operating environments. The NIST group, Lijun Ma, Oliver Slattery, and Xiao Tang, wanted to develop a way to use existing detectors such as avalanche photodiode (APD) detectors, which work very well for detecting visible light and are widely used, but are ineffective for the detection of NIR.

frequency converter equipment

A lithium niobate waveguide (bottom left) combines a pump laser and a near-infrared signal, “up-converting” the signal to a visible wavelength. Two prisms (right) separate the signal from the combined beam and send it to an avalanche photodiode detector (top left), which reads the up-converted signal.

Credit: NIST
View hi-resolution image

Their approach was to adapt a technique developed two years ago at NIST for quantum cryptography that “up converts” photons at one frequency to a higher frequency. The technique promotes the IR photons up to the visible range using a strong, tunable laser. During the frequency conversion process, the narrow-band pump laser scans the IR signal photons and converts only those that have the desired polarization and wavelength to visible light. Once converted to visible light, the signal photons are easily detected by commercially available APDs. According to Tang, the new system enables the measurement of spectra with sensitivity of more than 1,000 times that of common commercial optical spectral instruments.

“Our key achievement here was to reduce the noise, but our success would not have been possible without the many years of work by others in this field,” says Tang. “We hope that our discovery will open doors for researchers studying diseases, pharmaceuticals, secure communications, and even solving crimes. We are very excited to make this technology available to the larger scientific community.”

* L. Ma, O. Slattery and X. Tang. Experimental study of high-sensitivity IR spectrometer with waveguide-based up-conversion detector. Optics Express. Vol. 17, No. 16. Aug. 3, 2009.


About The Author

NIST’s picture


Founded in 1901, the National Institute of Standards and Technology (NIST) is a nonregulatory federal agency within the U.S. Department of Commerce. Headquartered in Gaithersburg, Maryland, NIST’s mission is to promote U.S. innovation and industrial competitiveness by advancing measurement science, standards, and technology in ways that enhance economic security and improve our quality of life.