(a) Schematic of direct femtosecond laser writing of nonlinear photonic structures. (b) The 2D optical microscopic and (c) 3D nonlinear optical microscopic images of the resulting photonic structures, respectively.
As optical components tend to replace electronics in dealing with processing of enormous data stemmed from the internet revolution, there is growing impetus to integrate more photonic devices onto a single chip. In this respect, most research efforts in the last years have concentrated on silicon photonics. However, silicon lacks second-order optical nonlinearity for active photonics and, at telecommunication wavelengths, third-order nonlinear silicon devices typically suffer from the nonlinear absorption.
Recent developments in fabrication and microstructuring of single-crystalline LiNbO3 thin film (LiNbO3 on Insulator, LNOI) have rendered LNOI as a promising platform for integrated optics applications. LiNbO3 has excellent electro-optic, acousto-optic, and nonlinear optical properties. It can also be doped with rare-earth ions to transform it into a laser active material. Therefore, LNOI holds promise to be an ideal medium for the development of a wide range of extremely compact, active integrated devices.
In this project we will develop an entirely novel, “silver bullet” approach for micro-structuring of LNOI using tightly focused ultrashort laser pulses. The unique features of the interaction of high-intensity utrashort light pulses with matter allows us not only to tailor the second-order nonlinearity of LNOI with submicron accuracy, but also to overcome the deficiency of traditional techniques. The highly innovative character of this work will lead to generation of significant intellectual property in a critical area of multibillion dollar integrated photonics and optoelectronics market.