Shaping the power spectrum of ultra-wideband radio-frequency signals

We demonstrate the ability to tailor the power spectrum of ultra-wideband (UWB) RF waveforms via a photonics-based electromagnetic pulse shaper. We describe and experimentally demonstrate a waveform design methodology that allows us to achieve desirable power spectrum properties, such as broad bandwidth and minimal spectral ripple. As one example, we generate a 115% fractional-bandwidth impulsive waveform which spans the 3-10-GHz band, with ripple below +/- 1.5 dB over a 5-GHz band. Furthermore, by treating the RF spectral phase as a design parameter, we demonstrate how to achieve increased power spectral density. We illustrate the spectral design capabilities of our technique by presenting a variety of tailored UWB waveforms (including impulses, chirped signals, and arbitrary waveforms) with bandwidths that range from similar to 4 to 8 GHz.