Nanometer-sized copper sulfide hollow spheres with strong optical-limiting properties

CuS semiconductor nanometer-sized hollow spheres are successfully synthesized by using a soft-template method. A possible growth mechanism is proposed. The linear optical property of the CuS hollow spheres is examined by means of photoluminescence spectroscopy at room temperature. The optical-limiting (OL) property of these nanostructures is characterized by using a nanosecond Q-switched YAG laser and an optical parametric oscillator pumped with Surelite-III. A strong OL response is detected for the CuS hollow spheres in both visible and near infrared (NIR) spectral ranges, which makes these promising materials for applications such as the protection of human eyes or as optical sensors for high-power laser irradiation. The OL mechanism of the CuS hollow-sphere nanostructure may be the combination of free-carrier absorption (FCA) and nonlinear scattering.