Nanocrystalline Cr²⁺-doped ZnSe Nanowires Laser

By using femtosecond laser pulses to ablate microsized targets that are dispersed in liquid media, nanocrystalline Cr²⁺-doped ZnSe nanowires have been successfully fabricated for the first time. The phase and stoichiometries of the original materials are preserved while the sizes are reduced down to 30–120 nm for these nanowires. X-ray diffraction results show that the products are nanocrystalline ZnSe with cubic sphalerite structure. Scanning electron microscope results indicate that the products be ZnSe nanowires. The nanowires are usually 30–120 nm in diameter and several tens of micrometers in length. Photoluminescence of the nanocrystalline Cr²⁺-doped ZnSe nanowires shows strong emission at around 2000–2500 nm under excitation of 1300–2250 nm wavelength at room temperature. By using the Cr²⁺-doped ZnSe multiple nanowires as the gain medium, mid-infrared oscillation at 2194 nm has been established. The oscillation wavelength of the multiple nanowires laser is 150 nm shifted to shorter wavelengths in comparison with that of microsized powder random laser

Dynamic measurement of 2D refractive index distribution of NaCl solutions

<p>We demonstrate a simple and reliable method for measuring the two-dimensional refractive index (RI) distribution of transparent liquids, either homogeneous or inhomogeneous. The RI variation and the RI over the laser incident surface are measured by computing the phase shift of the interferograms as the optical path difference between the two beams passing through the sample liquid and air is changing. The phase shift is calculated by analyzing the interferograms by fast Fourier transform and a fringe shift counter. The RI change of the NaCl–water in the dissolving process was successfully measured by our method. This algorithm is stable, fast, efficient and of high accuracy up to 10⁻⁴. It holds potential for some applications that requires noncontact, and particularly for inhomogeneous transparent mediums.</p

Visualization 1.mp4

We realized scanning in a straight line by using two-step focusing method with the mask of 16 × 16. In the first step, the size of the dataset is 1000 and the number of epochs is 40. In the second step, the size of the dataset is 2000 and the number of the encoded pixels is 8 and the number of epochs is 40