  We use a drop-port geometry to study power transfer in silicon nitride
on-chip microresonator frequency comb generators. In sharp contrast with the
traditional transmission geometry, we observe smooth output spectra with
comparable powers in the pump and adjacent comb lines. An observation of
saturation in the drop-port output power is explained semi-empirically by
introducing pump saturation into a coupling of modes model. Autocorrelation
measurements are performed on the drop-port output, without the need to filter
out or suppress the strong pump line as is necessary in thru-port experiments.
Passively mode-locked pulses are observed with a normal dispersion microcavity.
