  We report on the development of all-fiber stand-alone Iodine-filled Photonic
Microcells demonstrating record absorption contrast at room temperature. The
microcell s fiber is made of inhibited coupling guiding hollow-core photonic
crystal fibers. The fiber-core loading with Iodine was undertaken at 10-1 -
10-2mbar vapor pressure using a novel gas-manifold based on metallic vacuum
parts with ceramic coated inner surfaces for corrosion resistance. The fiber is
then sealed on the tips and mounted on FC/APC connectors for better integration
with standard fiber components. The stand-alone microcells display Doppler
lines with contrasts up to 73% in the 633nm wavelength range, and an insertion
loss between 3 to 4dB. Sub-Doppler spectroscopy based on saturable absorption
has been carried out to resolve the hyperfine structure of the P(33)6-3 lines
at room temperature with a full-width at half maximum of 24MHz on the b4
component with the help of lock-in amplification. Also, we demonstrate
distinguishable hyperfine components on the R(39)6-3 line at room temperature
without any recourse to signal-to-noise ratio amplification techniques.
