Mid-infrared Cr2+:ZnSe random powder lasers

4.24 μm mid-infrared laser based on a single Fe2+-doped ZnSe microcrystal

In this Letter, we report for the first time, to the best of our knowledge, a micron-sized mid-infrared Fe²⁺:ZnSe laser based on a single microcrystal. Typical laser emissions centering at 4.24 μm are observed from a selected Fe²⁺-doped ZnSe microcrystal under 2.94 μm excitation of Er:YAG laser at room temperature. The laser linewidth is ∼10  nm, the pulse width is ∼50  ns, and the lasing threshold is ∼7.4  mJ/pulse. The lasing wavelength is stable as the pump energy increases and is consistent with the strong absorption position of carbon dioxide in the atmosphere.

Nanocrystalline Cr(2+)-doped ZnSe nanowires laser

By using femtosecond laser pulses to ablate microsized targets that are dispersed in liquid media, nanocrystalline Cr(2+)-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 Cr(2+)-doped ZnSe nanowires shows strong emission at around 2000-2500 nm under excitation of 1300-2250 nm wavelength at room temperature. By using the Cr(2+)-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.

Blue-light-emitting ZnSe random laser

We observed blue-light-emitting random laser action with coherent feedback in ZnSe particles. Below the threshold excitation, we observed a broad spontaneous emission band peaking at approximately 470 nm. Above the threshold, several discrete lasing lines appear at the center of the spontaneous emission band (approximately 475 nm). The linewidth of each lasing emission is less than 0.4 nm, which is about 40 times narrower than that of the spontaneous emission band. Although the lasing intensity of each line varies from pulse to pulse, the peak wavelengths do not shift significantly. The lasing emission was also found to radiate in all directions.