  We demonstrate 1D simultaneous laser cooling of $^{87}$Rb and $^{85}$Rb atoms
using an optical frequency comb. By adjusting the pulse repetition frequency
and the offset frequency, the frequency comb spectrum is tuned to ensure that
two distinct frequency comb modes are simultaneously red-detuned from the
cooling transitions, one mode for each species. Starting from a pre-cooled
cloud of $^{85,87}$Rb atoms at above-Doppler temperatures, we show simultaneous
cooling of both species down to the Doppler temperature using two
counter-propagating $\sigma$$^{+}$/$\sigma$$^{-}$-polarized beams from the
frequency comb. The results indicate that simultaneous dual-species frequency
comb cooling does not affect the cooling characteristics of individual atomic
species. The results of this work imply that several atomic species could be
cooled simultaneously using a single frequency comb source. This comb-based
multi-channel laser cooling could bring significant advances in multi-species
atom interferometers for space applications and in the study of multi-species
interactions.
