  We study theoretically the transmission spectra in one-dimensional photonic
quasicrystals, made up of SiO$_2$($A$) and TiO$_2$($B$) materials, organized
following the Octonacci sequence, where the $n$th-stage of the multilayer
$S_{n}$ is given by the rule $S_{n}=S_{n-1}S_{n-2}S_{n-1}$, for $n\geq 3$ and
with $S_{1}=A$ and $S_{2}=B$. The expression for transmittance was obtained by
employing a theoretical calculation based in the transfer-matrix method. To
normally incident waves, we observe that, for a same generation, the
transmission spectra for TE and TM waves are equal, at least qualitatively, and
they present a scaling property where a self-similar behavior is obtained, as
an evidence that these spectra are fractals. The spectra show regions where the
omnidirectional band gaps emerges for specific generations of Octonacci
photonic structure, except to TM waves. For TE waves, we note that all of them
have the almost same width, for different generations. We also report the
localization of modes as a consequence of the quasiperiodicity of the
heterostructure
