NIST Offers New Calibration Service for Wavemeters

For more than three decades, the National Institute of Standards and Technology (NIST) has calibrated the wavelengths of lasers used in industry, academia, and government laboratories. NIST has now expanded its service to include the calibration of wavemeters—specifically those that measure light at telecommunication wavelengths, which are used to transmit data over fiber-optic cables.

A typical fiber-optic cable uses several wavelengths to carry information, with each wavelength constituting a separate channel for data. To keep up with the demand for data transmission, engineers and scientists are feeding a greater number of telecommunication wavelengths into each cable.

As a consequence, calibration of the devices that measure these wavelengths has become more crucial. For example, if two closely spaced wavelengths traveling in the same cable overlap because they have not been precisely measured, it could severely hamper the relay of information.

That’s why Johnny Jiménez, a metrologist with the Costa Rican Institute of Electricity, an autonomous public arm of the government of Costa Rica, came to NIST last August. He arrived at Patrick Egan’s dimensional metrology laboratory for a two-month stay, carrying a wavemeter from his institute.

“With new technological trends, new fiber-optic network standards and higher data transmission requirements worldwide, there’s a pressing need to expand the range of wavelengths measured by wavemeters and improve the accuracy of these devices,” said Jiménez. In addition to improving the capabilities of fiber-optic network, more precise wavemeters support the development of new materials and equipment with properties that depend on the chosen wavelength, he added.

To calibrate a wavemeter, Egan relies on an optical frequency comb—a series of evenly-spaced frequencies that act like ticks on a ruler to measure light. The comb is linked to an oscillator that vibrates at a frequency steered by the global positioning system, allowing the calibration to be directly traceable to the International standard unit for the second.

Egan described the method online on November 7 in Metrologia.

“NIST was able to calibrate our standard wavemeter at a specific wavelength range of great importance with a level of accuracy unrivaled by any other national metrology institute,” said Jiménez.

Egan says he expects the demand for wavemeter calibrations to increase as telecommunication networks carry an increasing amount of high-speed data. NIST now calibrates wavemeters at telecommunication wavelengths ranging from 1520 to 1570 nanometers (nm), and at a single wavelength of red light, 633 nm. Jiménez extended the capability to the important telecommunication wavelengths of 1310 nm and 1625 nm.

Upon request, Egan said, NIST may consider calibrating wavemeters that measure other wavelengths.

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Paper: Wavemeter calibration by frequency comb. P. F. Egan. Metrologia, vol. 61, no. 6, published Nov. 7, 2024. DOI 10.1088/1681-7575/ad8927