A 9.8 W, continuous wave (CW) operation of a a-cut Tm,Ho:YAlO<sub>3</sub> (Tm,Ho:YAP) laser at 2119.2 nm is reported in this paper. The Tm,Ho:YAP crystal, which was cooled at the temperature of 77 K, was double end-pumped by two 14.0- W fiber-coupled laser diodes at 793.5 nm. An optical-optical conversion efficiency of 35% was acquired, corresponding to a slope efficiency of 37.8%.
Infrared-to-visible upconversion emission intensities are investigated in Li<sup>+</sup>/Er<sup>3+</sup>, Li<sup>+</sup>/Ho<sup>3+</sup>/Yb<sup>3+</sup> and Li<sup>+</sup>/Tm<sup>3+</sup>/Yb<sup>3+</sup>
codoped oxide nanocrystals. By introducing Li<sup>+</sup> ion, the upconversion emission intensity of rare-earth ions are
significantly enhanced comparing with that without the Li<sup>+</sup> ion. The local structure around Er<sup>3+</sup> and Ho<sup>3+</sup> ions are studied
by the extended X-ray absorption fine structure spectroscopy. After doping Li<sup>+</sup> ion, both the average bond lengths of
Er-O and Ho-O are decreased.
Proc. SPIE. 9142, Selected Papers from Conferences of the Photoelectronic Technology Committee of the Chinese Society of Astronautics: Optical Imaging, Remote Sensing, and Laser-Matter Interaction 2013
Polarization measurement approaches only using polarizer and grating is present. The combination polarizers consists of two polarizers: one is γ degree with the X axis; the other is along the Y axis. Binary grating is covered by the combination polarizers, and based on Fraunhofer diffraction, the diffraction intensity formula is deduced. The polarization state of incident light can be gotten by fitting the diffraction pattern with the deduced formula. Compared with the traditional polarization measurement method, this measurement only uses polarizer and grating, therefore, it can be applied to measure a wide wavelength range without replacing device in theory.
Er<sup>3+</sup> and Li<sup>+</sup> codoped Y<sub>2</sub>O<sub>3</sub> nanocrystals has been prepared by sol-gel method. Upconversion spectrum
and properties of Er<sup>3+</sup> has been studied under excitation at 976 nm. Fluorescence intensity ratio of
<sup>2</sup>H<sub>11/2</sub> and <sup>4</sup>S<sub>3/2</sub> subband levels in the Er<sup>3+</sup> and Li<sup>+</sup> codoped Y<sub>2</sub>O <sub>3</sub> nanocrystals have been studied as a
function of temperature. In the temperature range of 295-723 K, the <i>I<sub>525nm</sub>/I<sub>561nm</sub></i> has the highest
thermal sensitivity the maximum sensitivity is approximately 0.016 K<sup>-1</sup>. The Y<sub>2</sub>O<sub>3</sub>: Er<sup>3+</sup>/Li<sup>+</sup>nanocrystals with high fluorescence efficiency and the higher temperature revolution, indicated that it is
promising for applications in optical high temperature sensor.