Event detection via THz generation with flat nonlinear optics [Invited]

Event detection is a key feature in many applications and is often achieved digitally by comparing sequential frames and detecting changes or patterns that signify an event. While digital systems dominate most applications, optical analog methods are receiving increasing attention in areas requiring speed or operation in challenging conditions. Here we demonstrate how a simple thin film of AlGaAs can be used to realize ultrafast event detection by exploiting the THz signal generated by the difference-frequency of optical events.