Cover Picture: Efficient Two-Photon Excited Amplified Spontaneous Emission from Organic Single Crystals (ChemPhysChem 9/2010) (page 1793)
Hong Xia, Jie Yang, Hong-Hua Fang, Qi-Dai Chen, Hai-Yu Wang, Xiao-Qiang Yu, Yu-Guang Ma, Min-Hua Jiang and Hong-Bo Sun
Version of Record online: 14 JUN 2010 | DOI: 10.1002/cphc.201090040
Compared to currently widely used excimer and dye lasers, solid-state lasers offer obvious technical advantages. Two categories of solid-state laser technologies, namely sum-frequency of second harmonic generation (SHG) in nonlinear laser crystals and two-photon pumped (TPP) upconversion lasing of organic molecules are being adopted for wavelength shortening, of which the latter is more important, because phase matching requirements are eliminated. So far, TPP lasing has been realized for many applications, all based on molecules distribution into a polymer matrix. On p. 1871, Q. Yu, H. Sun et al. report Tpp upconversion cavityless lasing from an organic single crystal. The use of high quality crystals as the laser medium, significantly increasing the gain and the lasing efficiency and surmounting the shortcomings of polymer systems such as poor conduction, which results in a low damage threshold and short lasing lifetime, may pave the way to practical use for TPP solid-state laser sources.