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1991—NIST begun offering routine calibration services for laser vacuum wavelength. Industrial users of laser interferometers need traceability of their measurements to national and international standards, and NIST measurements of the laser wavelength provide the critical link in achieving this traceability.

Engineer John Lowe with NIST-7
Engineer John Lowe with NIST-7.
Credit: NIST
1993—The first laser-based atomic clock, known as NIST-7, began operation. Designed by NIST physicist Robert Drullinger and colleagues, NIST-7, which used lasers to optically excite atoms to the desired state and to detect their fluorescence afterwards, served as the U.S. civilian time and frequency standard until 1999. NIST-7 replaced earlier, less accurate atomic clocks (dating back to 1949) that relied on magnets to select and detect the state of the atoms.

1993—NIST issued Standard Reference Material (SRM) 2520 for calibrating systems used to measure the geometry of optical fibers. NIST measurements are a key enabler of modern communications, which rely on lasers to transmit light signals through fiber-optic cables. Industry hit an early manufacturing barrier when optical fiber from different vendors could not interconnect without excessive signal loss due to lack of diameter control. NIST responded by developing SRM 2520, a short length of bare fiber in an aluminum housing, and fiber-optic test procedures for measuring diameter. In 1980, fiber cost $1 per meter and measurements constituted 20 percent of manufacturing cost; by 2005 the cost was down to 5 cents per meter and measurements were just 10 percent of manufacturing cost. NIST traceability enhanced competitiveness: An international study showed the United States had three times better diameter measurements than Europe and Asia.

Excimer laser beam before and after servicing to produce more uniform intensity.
Excimer laser beam before and after servicing to produce more uniform intensity.
Credit: NIST
1994—NIST began offering the world's first measurement and calibration services for excimer lasers, which emit short, high-energy pulses of ultraviolet radiation. Excimer lasers were used initially in advanced semiconductor manufacturing and later in common vision correction procedures such as LASIK (laser-assisted in situ keratomileusis).

NIST physicist Eric Cornell
NIST physicist Eric Cornell
Credit: © Geoffrey Wheeler
1995—A collaboration between NIST and the University of Colorado at Boulder (CU), using laser and evaporative cooling techniques, resulted in the creation of a new form of matter, the Bose-Einstein condensate (BEC). The first BEC was a tiny ball of about 2,000 ultracold rubidium atoms melded into a "superatom", behaving as a single entity. Dozens of laboratories around the world have replicated the work and are continuing research in the field. For the BEC discovery, Eric Cornell of NIST and Carl Wieman of CU were awarded the 2001 Nobel Prize in Physics. They shared the prize with Wolfgang Ketterle of the Massachusetts Institute of Technology.

1998—NIST researchers Sarah Gilbert and Bill Swann developed NIST Standard Reference Materials (SRMs) to provide accurate laser wavelength measurements. This work was critical to enable advances in wavelength division multiplexing (WDM), a technique for layering multiple signals over a single fiber for optical communications. These SRMs can also be used to calibrate optical spectrum analyzers and other test equipment with sub-picometer (trillionth of meter) accuracy.

Illustration of NIST-F1 design
Illustration of NIST-F1 design.
Credit: Jeffrey Aarons
1999—The NIST-F1 cesium fountain clock, designed and operated by NIST physicist Steve Jefferts and colleagues, came online as the U.S. civilian time and frequency standard. Fountain clocks, which rely on a fountain-like movement of atoms that are cooled and then tossed upward by lasers, had been imagined many years before but were not practical until laser cooling of neutral atoms became routine. As of 2009, NIST-F1 is the best primary standard for time and frequency in the world, so accurate that it will neither gain nor lose 1 second in about 100 million years. Cesium clocks use microwave frequencies and will be replaced in the future by even more accurate atomic clocks operating at higher optical frequencies.

1990s—The invention of ultrafast lasers, coupled with earlier work on laser stabilization, led to the creation of laser pulses short enough to produce "combs" of laser frequencies spanning the visible spectrum. (A shorter pulse produces a wider comb.) Optical frequency combs are key to the design of next-generation atomic clocks. Among NIST contributions, physicists Jan Hall and Steve Cundiff verified the idea of using microstructured "magic" fiber to produce white light composed of a supercontinuum of infrared, red, green and blue light—a comb of coherent optical frequencies.

Created June 4, 2010, Updated September 21, 2016