High Harmonic Generation from Laser-Induced Plasmas of Ni-Doped CsPbBr₃ Nanocrystals: Implications for Extreme Ultraviolet Light Sources

The development of versatile two-dimensional (2D) nanocrystals (NCs), with superior nonlinear optical (NLO) properties, is essential for various applications in photonics and optical communications. In this work, we demonstrate efficient high-order harmonic generation (HHG) from the laser-induced plasmas (LIPs) of CsPbBr3 and Ni-doped CsPbBr3 NCs. The present study has been directed at unraveling the role of dopants in the emission of intense harmonics from the LIP of purposefully engineered CsPbBr3 colloidal NCs. The trend observed in the harmonic yield enhancement is found to be similar to the increase in their third-order NLO properties [nonlinear refractive index (n2), nonlinear optical susceptibility (χ(3))] of the same NCs studied at a wavelength of 800 nm. Ni-doped CsPbBr3 NCs containing plasma spreading allowed optimization of the delay between nanosecond (ns) heating pulse and driving pulse (single-color pump) for an enhancement in the conversion efficiency of harmonics. We believe that the emission of harmonics from the LIPs of these pristine, Ni-doped CsPbBr3 colloidal 2D NCs reported here provides the means to address the increase in the efficiency of extreme ultraviolet radiation, useful in attosecond spectroscopic studies.