  We investigated the temperature- and frequency-dependent optical scattering
rates in the pseudogap phase of cuprates using model pseudogap and
electron-boson spectral density (EBSD) functions. We obtained the scattering
rates at various temperatures below and above a given pseudogap temperature
using a generalized Allen's (or Sharapov's) formula, which has been used to
analyse the measured optical spectra of correlated electron systems with a
non-constant density of states at finite temperatures. The pseudogap and EBSD
functions should be temperature dependent to simulate the Fermi liquid-like
behaviour of underdoped cuprate systems observed in optical studies. Therefore,
the observed Fermi liquid-like behaviour can be understood by considering the
combined contribution from the T-dependent EBSD function and the T-dependent
pseudogap. We also obtained the optical conductivity spectra from the optical
scattering rates and analyzed them to investigate intriguing electronic
properties. We expect that our results will aid in understanding the Fermi
liquid-like optical response in the pseudogap phase and in revealing the
microscopic pairing mechanism for superconductivity in cuprates.
