  We present a thorough experimental investigation of the loading process of
laser-cooled atoms from a magneto-optical trap into an optical dipole trap
located inside a hollow-core photonic bandgap fiber, followed by propagation of
the atoms therein. This, e.g., serves to identify limits to the loading
efficiency and thus optical depth which is a key parameter for applications in
quantum information technology. Although only limited access in 1D is available
to probe atoms inside such a fiber, we demonstrate that a detailed
spatially-resolved characterization of the loading and trapping process along
the fiber axis is possible by appropriate modification of probing techniques
combined with theoretical analysis. Specifically, we demonstrate the loading of
up to $2.1 \times 10^5$ atoms with a transfer efficiency of 2.1 % during the
course of 50 ms and a peak loading rate of $4.7 \times 10^3$ atoms ms$^{-1}$
resulting in a peak atomic number density on the order of $10^{12}$ cm$^{-3}$.
Furthermore, we determine the evolution of the spatial density (profile) and
ensemble temperature as it approaches its steady-state value of $T=1400$
$\mu$K, as well as loss rates, axial velocity and acceleration. The spatial
resolution along the fiber axis reaches a few millimeters, which is much
smaller than the typical fiber length in experiments. We compare our results to
other fiber-based as well as free-space optical dipole traps and discuss the
potential for further improvements.
