Reconfigurable RF-Waveform Generation Based on Incoherent-Filter Design

Radio-frequency (RF) waveform generators are key devices for a variety of applications, including radar, ultra-wideband communications, and electronic test measurements. Following advances in broadband coherent pulsed sources and pulse-shaping technologies, reconfigurable RF waveform generators operating at bandwidths $>$1 GHz have become a reality. In this work, we demonstrate reconfigurable RF waveform generation using broadband spectrally incoherent optical sources. This is achieved in two steps. First, we implement an RF incoherent filter. The energy spectrum of the optical source is conveniently apodized using a commercially available computer-controlled D-WDM channel selector with 100-GHz resolution. The channel controller provides high flexibility for shaping the optical source energy spectrum and, hence, high reconfigurability capabilities in terms of the RF filter. Second, we show that by applying a short baseband electrical waveform to the input of the RF filter, the output RF spectrum of the electrical signal is a mapped version of the designed RF filter transfer function. Specifically, we illustrate the capabilities of our technique by generating RF signals with $\sim$ 10 GHz bandwidth and tunable repetition rate. Finally, we discuss how this method can be scaled up to the millimeter-wave range with current technology.