Lead halide perovskite nanocrystals have established the special consideration of scholars in the last few years due to their cutting-edge nonlinear optical properties and progress in unpretentious synthetic procedures. These materials have efficient applications in various optoelectronic devices. Th enhancement of nonlinear optical properties of the perovskites can be influenced by doping of transition metal ions.
Therefore, it is important to know their optical properties and applications in the emission of higher-order harmonics from their plasma plumes.
A research team from the GPL photonics Laboratory, Changchun Institute of Optics, Fine Mechanics, and Physics (CIOMP) of the Chinese Academy of Sciences (CAS) studied the effect of Ni dopants on CsPbBr3 nanocrystals in terms of the changes of third-order nonlinear optical (NLO) properties measured at strong absorption wavelength 400 nm and emission of higher-order harmonics from single (800 nm) and two-color (800 nm+400 nm) chirp-free (35 fs) and chirped (±135 fs) driving pulses. The study was published in Journal of Materials Science. The results indicated that NLO properties depend on the pump wavelength, and the enhancement of nonlinear absorption and refraction coefficients are achieved at 800 nm wavelength. In contrast, those coefficients are decreased at pump wavelength 400 nm for Ni-doped CsPbBr3 compared to pure CsPbBr3. The doping of nanocrystals by Ni at different percentile changes meaningfully altered the nonlinear absorption mechanism. The reverse saturable absorption was followed by the saturable absorption with increasing input laser intensity.
However, in both cases, i.e., at 800 nm (single-color pump, SCP) and 800 nm +400 nm (two-color pump, TCP), the intensity of the high-order harmonics and the cut-off was increased for Ni-doped CsPbBr3 than pure CsPbBr3. Due to the presence of additional plasma components of Ni, the high order harmonics intensity and the cut-off was achieved.
Interestingly, the enhancement/decrement of NLO properties measured at 800 nm and 400 nm is a similar way to enrichment of harmonics measured by SCP and TCP, respectively.
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