A new chapter for nonlinear optics

This is the result of a new study recently published in Nature Photonics by Xinyi Xu, PhD student of Columbia University, and Chiara Trovatello, postdoctoral research scientist at the Physics Department of Politecnico di Milano, together with Prof. Giulio Cerullo from the Physics Department of Politecnico di Milano, Dmitri N. Basov and P. James Schuck from the Columbia University of New York City (US).

“Optical fibers, bar code readers, light scalpels for precision surgery… the innumerable applications which have revolutionized our daily life rely exclusively on one tool: the laser. Each laser, however, emits light only at one specific wavelength and in order to generate new colors one can make use of specific crystals exploiting nonlinear optical processes.

The miniaturisationtrend, which has dominated the world of electronics, enabling the realisation of powerful consumer devices, such as smartphones and tablets, is now moving the world of lasers and their applications, which constitute the so-called field of photonics. For this reason, it is necessary to realise nonlinear processes inside thinner and thinner crystals," said Chiara Trovatello, author of the study.

"The typical nonlinear crystal thickness is on the order of a millimiter. In this study we have proven that a new nonlinear material – the 3R crystal phase of molybdenum disulfide – over a thickness of few hundreds of nanometers (1 nm = 10-9 m) can achieve an unprecedent nonlinear optical gain. This study sets the ground for a new revolution in the field on nonlinear optics.”

This crystal opens innumerable future applications, which could be directly integrated on a micrometric optical chip, reducing the typical size of nonlinear optical devices. Among the most relevant applications: optical amplifiers, tunable lasers and quantum light generators over nanometer length scales.

“On-chip nonlinear application will reinvent photonic devices through thinner and more compact designs. This is thanks to fundamental research, which allows us to get one step closer to the future of science and technology,” concluded Prof. Cerullo.