The Fiber Sources and Applications Group at NIST has a long-standing focus on the application of optical frequency combs to time-frequency transfer and ranging. This focus places us at an intersection of optics, electrical engineering and fundamental physics, as we leverage the advent of robust optical frequency combs along with advanced digital signal processing techniques to achieve sub-femtosecond timing over 100-km open air paths and at terrestrial velocities.
We are currently focused on (i) the continued advancement of optical methods of transferring time and frequency information for practical terrestrial and satellite operation, (ii) the combination of precision ranging with time transfer, (iii) the use of optical time transfer for comparison of optical clocks and tests of fundamental physics, and (iv) the establishment of phase coherence across networks for distributed coherent sensing.