Photonic generation of CW sub-THz and THz waves using an efficient Gain-Switching based VCSEL optical frequency comb

A Continuous Wave (CW) millimeter-wave photonic synthesizer based on Difference Frequency Generation (DFG) is presented. This system encompasses an Optical Frequency Comb Generator (OFCG), an optical mode selection stage and a high-bandwidth photodetector. The employed OFCG is a novel design based on Gain-Switching modulation of a VCSEL. This new OFCG offers equivalent optical span than commonly employed designs with fewer component count, and especially less input RF power, paving the way to stable, widely tunable, energy-efficient and compact OFCGs. In this paper, the application of this OFCG to sub-THz wave generation with ultra-low phase noise and ultra-high resolution is presented.