We build ring resonators to assess the potentialities of Kagome Hollow-Core
Photonic Crystal Fibers for future applications to resonant rotation sensing.
The large mode diameter of Kagome fibers permits to reduce the free space
fiber-to-fiber coupling losses, leading to cavities with finesses of about 30
for a diameter equal to 15 cm. Resonance linewidths of 3.2~MHz with contrasts
as large as 89\% are obtained. Comparison with 7-cell photonic band gap (PBG)
fiber leads to better finesse and contrast with Kagome fiber. Resonators based
on such fibers are compatible with the angular random walk required for medium
to high performance rotation sensing. The small amount of light propagating in
silica should also permit to further reduce the Kerr-induced non-reciprocity by
at least three orders of magnitudes in 7-cell Kagome fiber compared with 7-cell
PBG fiber
