Modeling Optical Time and Frequency Generation and Transfer Systems

Developing a unique set of computational algorithms based on dynamical systems theory that allow the rapid and unambiguous determination of the stability and noise performance of lasers and microresonators.

DARPA, Arlington, Virginia

As originally proposed, this research was closely tied to work that was led by Nathan Newbury at NIST, and the principal goal was to support the development of advanced laser sources.

In order to develop robust, carrier-envelope-phase-locked sources that can be transported without losing lock, the Newbury team used semiconductor saturable absorbing mirrors (SESAMs) to provide saturable absorption in their laser systems. This technology replaced nonlinear polarization rotation using the Kerr effect in optical fibers to provide the saturable absorption. As was demonstrated theoretically and the Newbury group had seen experimentally, nonlinear polarization is not a stable source of saturable absorption because the polarization state of standard optical fibers varies randomly due to environmental perturbations. The use of SESAMs, combined with polarization-preserving fibers, solved this problem. However, it led to some unexplained issues. First, it was found that it was not possible to operate too close to the zero dispersion wavelength. Second, it was found that in some cases, parasitic frequency sidebands appeared.