Hematene Nanoflakes: A non-van der Waals material with superior nonlinear optical properties

Stable and efficient optical limiters for eye and sensor protection have been of great demand ever since the advent of high-power lasers. In this study, we report the preparation of highly stable hematene nanoflakes for optical limiting applications by a facile exfoliation method from a low-cost, non-van der Waals material. Optical and structural characterization have been carried out to confirm the structure, morphology and composition of the hematene nanoflakes. Open aperture Z-scan measurements have been carried out in near-transparent samples (87% linear transmission at the excitation wavelength of 532 nm), using 5 ns laser pulses. Despite the high transparency of the sample, a high nonlinear absorption coefficient of 12.5 cm/GW has been determined, signifying the potential of this material for fabricating highly efficient optical power limiting devices.