  We demonstrate repetition-rate downsampling of optical frequency combs by way
of pulse gating. The reduced repetition rate enables increased pulse energy,
facilitating efficient spectral broadening and f-2f interferometry. To explore
the technique, we downsample a 250 MHz repetition-rate comb to 25 MHz and
detect the carrier-envelope offset frequency of the downsampled pulse train. We
investigate the effects of pulse gating on the noise properties of the pulse
train and the limitations of the technique by characterizing the phase-noise
spectrum of the downsampled comb and deliberately imposing timing jitter on the
pulse gate. We show that, up to an expected reduction modulo the new repetition
rate, downsampling neither shifts nor introduces noise to the carrier-envelope
offset frequency of the comb above the level of several microhertz.
Additionally, we discuss the effect of downsampling on the spectrum of
intensity fluctuations of the optical pulse train. Finally, we discuss some
practical considerations relevant for the application of the technique to
frequency combs with repetition rates in the 10 GHz range and higher.
