Photonics for electronic inteference suppression

Analog optics [1], commonly termed microwave photonics [2], is a decades-old field that offers well-cited advantages over analog and digital electronics. The two most important features in most, if not all, deployable use cases are low propagation loss in fiber and wide bandwidth. Indeed, the massive fiber telecommunications industry was born from simultaneous utilization of these two advantages over other signal transport means. Avionic platforms present a host of analog signal paths but the lack of long transmission distances results in a difficult case for the insertion of microwave photonics technology. That is, the penalty in noise figure when converting between the electronic and optical domain is not recouped over typical avionic transmission distances. However, the last six years have seen a rapid increase in the study of microwave photonics techniques for radio frequency (RF) interference mitigation, which does not necessarily take advantage of the low loss in fiber. Military and commercial airborne platforms might benefit from such techniques. The state of the art in photonics for RF interference mitigation is reviewed here, suggesting that a layered approach utilizing photonics, analog electronics and digital electronics has strong potential.