  We propose a time-varying optimal window width (TVOWW) selection scheme to
optimize the performance of several nonlinear-type time-frequency analyses,
including the reassignment method, and the synchrosqueezing transform (SST) and
its variations. A window rendering the most concentrated distribution in the
time-frequency representation (TFR) is regarded as the optimal window. The
TVOWW selection scheme is particularly useful for signals that comprise
fast-varying instantaneous frequencies and small spectral gaps. To demonstrate
the efficacy of the method, in addition to analyzing a synthetic signal, we
study an atomic time-varying dipole moment driven by two-color mid-infrared
laser fields in attosecond physics.
