We study photonic Bloch oscillations (PBO's) in various quasiperiodic diele
ctric structures. Photons, like electrons, may experience confinement withi
n inclined allowed optical bands of photonic structures, which results in a
characteristic photonic Wannier-Stark ladder (PWSL) and PBO's analogous to
electronic Bloch oscillations in crystals subjected to an electric held. I
n the photonic case the role of the electric held is played by a gradient o
f the size of the elementary cell of the optical crystal. The photonic band
structure for laterally confined Bragg mirrors with circular cross section
varying along the longitudinal axis is calculated analytically by means of
the coupled-mode theory for structures surrounded laterally either by a me
tal or by air. Using the scattering state technique, we demonstrate that in
porous silicon metallic Bragg reflectors the scattering states form a seri
es of discrete levels with a constant interlevel spacing of about 5 meV, an
d show that PBO's occur in these structures with a period of about 1 ps at
room temperature. PBO's and a PWSL with a comparable period and interlevel
spacing are demonstrated in planar multiple-microcavity structures based on
III-V semiconductors with cavity length varying along the growth axis. The
se structures are very promising, since they do not require any lateral con
finement, thus avoiding dephasing mechanisms introduced by etching at the l
ateral sidewalls that can hinder the observation of PBO's.