In the 1960s, physicists showed how light could interact with itself in intriguing ways thanks to a process known as second-harmonic generation. In the right kind of material, two photons of a certain frequency can interact to produce another photon of twice the frequency, turning red light into green, for example. Since then, physicists have exploited these non-linear optics in techniques ranging from precision measurement to quantum computing.
Yet, one persistent challenge has remained. Nonlinear optical devices must be crafted with a single, unchangeable function determined during fabrication. And this limits their utility and function.
Now that looks set to change thanks to the work of Ryotatsu Yanagimoto at Cornell University in Ithaca, and colleagues, who have unveiled a programmable photonic chip that promised to reshape optical science and the technology it enables.
A key process in non-linear optics is phase matching—the ability to synchronize two different light waves to ...
