A new chapter for nonlinear optics

On nature photonics a research that shows the unprecedented performances of an extremely thin nonlinear material

new bidimensional semiconductor shows the highest nonlinear optical efficiency over nanometer thicknesses. 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 Department of Physics of Politecnico di Milano, together with Prof. Giulio Cerullo from the Department of Physics of Politecnico di Milano, Dmitri N. Basov and P. James Schuck from the Columbia University.

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 miniaturization trend, which has dominated the world of electronics, enabling the realization 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 realize nonlinear processes inside thinner and thinner crystals.

Chiara Trovatello, author of the study

The typical nonlinear crystal thickness is on the order of a millimiter. In this study researchers 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 new 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 amplifierstunable lasers and quantum light generators over nanometer length scales.

On-chip nonlinear application will reinvent photonic devices through thinner and more compact designs.

Prof. Cerullo

H.P.C. & Quantum