TiB2 nanoparticles with a broadband nonlinear response for ultrafast pulse generation

Titanium boride (TiB2), as a kind of metal boride material, has exhibited extraordinary physical and chemical properties. However, few studies have been dedicated to determine their potential for application in nonlinear optics and ultrafast photonics. In this work, we first demonstrate the fabrication of a TiB2 saturable absorber (SA) with broadband absorption covering from 400 to 2500 nm. TiB2 nanoparticles (NPs) with an average size of 200 nm, good stability and high hardness are prepared through a metal-hydrolysis-assisted synthesis method. A Q-switched fiber laser operating at 1559 nm is realized by using a TiB2 film as the SA. By depositing the TiB2 NPs onto the side-polished fiber platform to fabricate the SA, ultrafast fiber lasers at 1.56 and 2 mu m can be achieved with pulse durations of 596 and 856 fs, respectively. Our experimental results validate that the integrated TiB2-based devices exhibit great potential as nonlinear optical media for ultrafast optical applications.