Generation of a Wideband OFC by the Correlation of Multiple Modes of a Gain-Switched Fabry Pérot Laser

We experimentally demonstrate two novel photonically integrable architectures of a wideband gain-switched optical frequency comb (OFC). The proposed method is based on correlating multiple modes of gain-switched Fabry-Pérot (GS-FP) laser. This is achieved by injection locking a GS-FP with an optimised signal generated by an source OFC and a dual-stage active demultiplexer. By employing such a configuration, we demonstrate the generation of two 6.25 GHz OFCs, spanning over 337.5 GHz and 875 GHz with expansion factors of 4 and 10, respectively. The optimisation of the OFC expansion for flatness and/or wide span, as required is also shown. Furthermore, a detailed comb line characterisation is reported, to highlight the spectral purity of the expanded comb portraying low linewidth (
$\sim $
85 kHz), a low relative intensity noise (RIN better than
$ - $
130 dB/Hz), and a high degree of phase correlation between lines (13 Hz beat tone width). Finally, active demultiplexing of the comb lines with various separations across the expanded OFC is reported, demonstrating its suitability for use in a superchannel-based flexible optical networks, mmW/THz generation and spectroscopy applications.