Semiconductor mode-locked laser dual comb system

A photonic integrated circuit-based mutually coherent dual frequency comb source comprising, on a same substrate of the photonic integrated circuit,

• a first and a second mode-locked laser for generating a first and second frequency comb respectively, each of the first and second mode-locked laser including a gain section and a saturable absorber section to provide mode-locking, and an extended optical cavity having a passive waveguide structure formed in a waveguide layer of the substrate,
• wherein at least said gain sections are provided as layered stacks of heterogeneously integrated III-V material, bonded to said substrate,
• a master laser for generating a continuous wave lasing line for simultaneous optical injection-locking of the first and second mode-locked laser, the master laser being configured to generate said continuous wave lasing line with a linewidth narrower than a frequency spacing between modes of the first and second frequency comb, and
• a connection arrangement, interposed between an output port of the master laser and a respective input port of each of the first and second mode-locked laser, for coherently transferring lasing light generated by the master laser to each mode-locked laser.