  The peculiarities of defect modes and reflection spectra of chiral photonic
crystals (CPC) with an isotropic defect for various thicknesses of the defect
layer was investigated. The peculiarities of the spectra of photonic density of
the state (DOS) and those of the intensity at the center of the defect were
investigated, too. It was shown that there is one more possibility of tuning of
laser emission - by the change of the defect layer thickness - in CPCs doped
with laser dyes (with resonance atoms) and with an isotropic defect. It was
shown that the given system can work as a tunable narrow-band filter (or
mirror) with tunable wavelength width and tunable location of frequency of the
complete transmittance (reflection) band. The radiation peculiarities of these
systems were discussed. It was shown that in certain conditions an anomalous
strong radiation can be observed for defect modes, and low - threshold laser
generation is possible, again, for these modes. It was also shown that
radiation suppression is possible for defect modes. The peculiarities of group
velocity, group velocity dispersion and nonreciprocity were studied.
