  We present a hybrid waveguide-fiber optical parametric oscillator (OPO)
exploiting degenerate four-wave mixing in tantalum pentoxide. The OPO, pumped
with ultrashort pulses at 1.55 $\mu$m wavelength, generated tunable idler
pulses with up to 4.1 pJ energy tunable between 1.63 $\mu$m and 1.68 $\mu$m
center wavelength. An upper bound for the total tolerable cavity loss of 32 dB
was found, rendering a chip-integrated OPO feasible as a compact and robust
light source.
