Efficient Subharmonic Frequency Conversion Using Space-Time Induced Bound States in the Continuum

Traveling-wave modulation has been extensively studied for its applications in parametric amplification, frequency conversion and non-reciprocity. It is often realized by applying staggered modulation signals to a set of discrete unit cells. This form of modulation will be referred to as spatially-discrete traveling-wave modulation (SDTWM). Recently, it has been shown that many of the frequency harmonics generated by SDTWM radiating structures are bound to the near field. These frequencies are confined by the space-time symmetry of SDTWM, and can be viewed as bound states in the continuum (BICs). In this paper, a SDTWM antenna design is proposed which leverages the localization of BICs to efficiently perform subharmonic frequency conversion.