A mode-locked laser diode (MLLD) provides a compact and reliable source of an optical frequency comb in the wavelength region. Such a source is attractive for establishing frequency reference grids for telecommunications. In light of recent developments of optical atomic clocks, [1] MLLD-based comb systems can play a central role in clock signal distribution/transfer to remote sites. A low-jitter MLLD also has important applications for ultrafast analog-to-digital conversion. Our experimental approach employs an ultrawide bandwidth optical frequency comb generated by a mode-locked femtosecond Ti:sapphire laser that is phase locked to a highly stable optical frequency standard. The optical second harmonic output of a MLLD will be compared against the Ti:sapphire comb in order to establish optical phase coherence between the two systems.