We experimentally explore the fluorescent spectrum of the Nd:YAP crystal to manifest the feasibility of tunable single- and multi-wavelength operations in the (4)F3/2 → (4)I11/2 transition. An intracavity etalon is subsequently exploited to effectively select spectral lines at 1073, 1080, and 1084 nm with the tunabilities of 0.56, 1.13, and 0.1 nm, respectively. We also experimentally obtain multi-wavelength oscillations among various intermanifold lines in the Nd:YAP crystal with the output powers on the order of several watts for each group. Employing the Cr(4+):YAG crystal to realize the passively Q-switched operation, the maximum average output powers as high as 2.3 and 3.5 W for 1073 and 1080 nm are obtained. The corresponding pulse energies at 1073 and 1080 nm are up to 177 and 159 μJ, respectively.

Hall, current–voltage, and deep-level transient spectroscopy measurements were used to characterize the electrical properties of metalorganic chemical vapor deposition grown undoped, Er- and Pr-implanted GaN films. Only one deep level located at 0.270 eV below the conduction band was found in the as-grown GaN films. However, four defect levels located at 0.300, 0.188, 0.600, and 0.410 eV below the conduction band were found in the Er-implanted GaN films after annealing at 900 °C for 30 min, and four defect levels located at 0.280, 0.190, 0.610, and 0.390 eV below the conduction band were found in the Pr-implanted GaN films after annealing at 1050 °C for 30 min. The origins of the deep defect levels are discussed.

The local environment of Er3+ in heavily Er-doped (Er, 2.5at.%) Si nanoclusters embedded in SiO2 films annealed at various temperatures was investigated by using the fluorescence-extended x-ray absorption fine structure spectroscopy. The results show that annealing caused a large effect on the local environment of Er3+ surrounded by O atoms and the 1.54μm photoluminescence intensity. The correlation between the local environment around Er3+ and the corresponding 1.54μm photoluminescence was discussed.