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Tara Fortier (Fed)

Dr. Tara Fortier is a group leader in the Time and Frequency Division. She leads a research group that performs both basic and applied research in the areas of precision optical and microwave metrology, as well as in laser source development. Her work focusses on utilizing phase stabilized modelocked lasers for the synthesis of highly stable optical and microwave signals from atomic and optical references. Her research efforts support the mission of the Time and Frequency division by providing the infrastructure for optical atomic calibration of NIST’s microwave timescale via synthesis and dissemination of low-noise and agile microwave signals, contributions of secondary time standards to international atomic time (TAI), and via the comparison of atomic clocks. The latter comparisons help to support international efforts toward redefinition of the SI second to optical atomic time. Additionally, atomic clock comparisons enable search for physics beyond the standard model, including tests of local position invariance, searches for time variation of fundamental constants, and provide constraints on the coupling of ultra-light dark matter to “normal” matter via the fine structure constant.

Dr. Fortier also serves NIST and the broader optics, physics and time/frequency community as a Fellow of the Optical Society of America and the American Physical Society (APS), and as an executive board member to the APS-Division of Laser Science, the NIST Women in STEM group, and the American Institute of Physics APL Photonics Journal. Dr. Fortier also serves as a NIST representative to the Inter-Agency Working Group on Quantum Workforce Development (under the White House Office of Science and Technology Policy.) She is strongly committed and active in supporting DEI&A efforts via development of inclusive organizational policies within NIST, at international conferences and within professional societies, and via personal and professional efforts towards outreach and mentorship.

Google Scholar Page

Research Appointments

  • 2019-present: Project Leader, NIST Time & Frequency Division. 
  • 2018 – present: Graduate Faculty, University of Colorado.
  • 2006-2019: Physicist, NIST/Dep. of Physics, University of Colorado, Boulder. 
  • 2006-2004:  Postdoctoral Director’s Fellow, NIST, Boulder/LANL.  
  • 1998-2003:  Research Assistant, JILA/Dept. of Physics, University of Colorado Boulder. 
  • Spring 1998: Research assistant, NRC Ottawa, Canada: Ultrafast Phenomena Group. 
  • Summer 1997: Research assistant, NRC Ottawa, Canada: Molecular Interface Group. 
  • Fall 1996: Research assistant, NRC Ottawa, Canada: Optoelectronics Group. 
  • Summer 1995: Research Assistant, Canadian Space Agency, Varennes Quebec. LIDAR group. 
  • Summer 1994: Research Assistant, Hydro Quebec, Varennes Quebec. Cables Group. 

Guest Researcher Appointments

  • 05/2016-08/2015: National Physical Laboratory, Teddington, United Kingdom
  • 08/2006-11/2006: University of Western Australia, Perth Australia

Scientific/programmatic output 


  • U.S. Patent Application serial number 14/872,078 for “SIGNAL GENERATOR, PROCESS FOR MAKING AND USING SAME”, patent granted 

Book Chapters: 

  • T.M. Fortier, D.J. Jones, J. Ye and S. T. Cundiff, “Phase stabilization of modelocked lasers,” Ultrafast Optics, Springer Verlag 
  • D.J. Jones, S.T. Cundiff, T.M. Fortier, J.L. Hall, and J.Ye, "Carrier-Envelope Phase Stabilization of Single and Multiple Femtosecond Lasers," Few-Cycle Pulse Generation and Applications, F.X. Kärtner Ed., Springer Verlag 

Programmatic Documents/Reports: 

  • Report: “NIST DEI&A strategic plan” 


  • SPIE Harold E. Edgerton Award in High-Speed Optics 2023 
  • American Physical Society Fellow 2022 
  • Department of Commerce Bronze Medal 2021 
  • NIST-PML Excellence in Diversity, Equity, and Inclusion Award 2021 
  • NIST Diversity, Inclusivity and Equal Employment Opportunity (EEO) Award 2021 
  • Optical Society of America Fellow 2021 
  • NIST Outstanding Associate Award 2019 (NIST Associate contributor to the Department of Commerce Gold Medal) 
  • NIST Outstanding Associate Award 2017 
  • Outstanding Paper from IEEE Ultrasonics, Ferroelectrics and Frequency Control Society 2014 
  • Young Scientist Award - European Frequency and Time Forum 2008 
  • Postdoctoral Director’s Fellowship - Los Alamos National Labs 2004 
  • NSERC Postgraduate Fellowship A 2000  
  • NSERC Postgraduate Fellowship B 1998   
  • Entrance Fellowship, University of Colorado at Boulder 1998 
  • Walter Roudorf Medal for most outstanding graduate in Physics - Concordia University 1998


Improved interspecies optical clock comparisons through differential spectroscopy

May E. Kim, Will McGrew, Nicholas Nardelli, Ethan Clements, Youssef Hassan, Xiaogang Zhang, Jose Valencia, Holly Leopardi, David Hume, Tara Fortier, Andrew Ludlow, David Leibrandt
Comparisons of high-accuracy optical atomic clocks \citeLudlow2015} are essential for precision tests of fundamental physics \citeSafronova2018}, relativistic

High-performance, compact optical standard

Zachary Newman, Vincent N. Maurice, Tara Fortier, Connor Fredrick, Scott Diddams, John Kitching, Matthew Hummon
We describe a high-performance, compact optical frequency standard based on a microfabricated Rb vapor cell and a low-noise, external cavity diode laser operati

Frequency Ratio Measurements with 18-Digit Accuracy Using a Network of Optical Clocks

Kyle Beloy, Martha I. Bodine, Tobias B. Bothwell, Samuel M. Brewer, Sarah L. Bromley, Jwo-Sy Chen, Jean-Daniel Deschenes, Scott Diddams, Robert J. Fasano, Tara Fortier, Youssef Hassan, David Hume, Dhruv Kedar, Colin J. Kennedy, Isaac Kader, Amanda Koepke, David Leibrandt, Holly Leopardi, Andrew Ludlow, Will McGrew, William Milner, Daniele Nicolodi, Eric Oelker, Tom Parker, John M. Robinson, Stefania Romisch, Stefan A. Schaeffer, Jeffrey Sherman, Laura Sinclair, Lindsay I. Sonderhouse, William C. Swann, Jian Yao, Jun Ye, Xiaogang Zhang
Atomic clocks occupy a unique position in measurement science, exhibiting higher accuracy than any other measurement standard and underpinning six out of seven
Created September 17, 2019, Updated April 12, 2023