Abstract

Optical frequency comb injection on semiconductor lasers has been recently explored as a novel approach for selective amplification and spectral broadening of the original comb [1], and to trigger additional nonlinear dynamics [2]. Comb injection on multi-wavelength lasers (MWL), i.e., lasers designed to emit at multiple and controllable modes, could arguably be a new step forward in comb processing and even microwave signal generation, yet it remains vastly unexplored. Here we analyze experimentally and numerically, the dynamics of a four-wavelength laser under comb injection. We demonstrate broadening and multiplication of frequency combs around the un-injected modes at frequency offsets of 34.96 GHz, 68.67 GHz, and 1.396 THz from the original comb. We obtain an excellent qualitative agreement with multi-wavelength rate equation models, and show that both the broadening and the power of the multiplied combs are strongly correlated with the mode coupling, and the modal gain balance between injected and un-injected modes. This approach could be extended to increase the number of modes and the offset frequency beyond 10 THz, enabling unprecedented broadband comb processing.

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