  We report on phase-locking of two continuous wave infrared laser sources
separated by 100 THz emitting around 1029 nm and 1544 nm respectively. Our
approach uses three independent harmonic generation processes of the IR laser
frequencies in periodically poled MgO: LiNbO3 crystals to generate second and
third harmonic of that two IR sources. The beat note between the two
independent green radiations generated around 515 nm is used to phase-lock one
IR laser to the other, with tunable radio frequency offset. In this way, the
whole setup operates as a mini frequency comb (MFC) emitting four intense
optical radiations (1544 nm, 1029 nm, 772 nm and 515 nm), with output powers at
least 3 orders of magnitude higher than the available power from each mode
emitted by femtosecond lasers.
