An InP-based 10 GHz repetition rate mode-locked laser photonic integrated circuit is optically synchronized to mmWave comb sources. In particular, we achieve optical synchronization via regenerative harmonic injection locking to an electro-optically modulated frequency comb and a dissipative Kerr soliton both having a mmWave repetition rate of similar to 300 GHz resulting in an optical frequency division factor of 30x.