摘要:

Low‐frequency dielectric constant measurements vs temperature and electric field indicate that the ferroelectric transition in Pb3MgNb2O9is second order. The quadratic electro‐optic coefficients in Pb3MgNb2O9are approximately an order of magnitude smaller than those of KTN (KTa.65Nb.35O3); however, the electronic conduction effects and compositional inhomogeneity problems encountered in KTN are absent in Pb3MgNb2O9, thus making it a practically useful electro‐optic material.

ISSN:0003-6951    

DOI:10.1063/1.1754893

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Elastic surface waves in quartz have been excited at 316 MHz by a method which seems also to be promising for even higher frequencies up to a few GHz. The temperature dependence of the absorption in quartz has been studied between 2°K and 300°K. When the quartz is immersed in liquid helium, an additional attenuation due to radiation on longitudinal waves into the fluid occurs which turns out to be noticeably higher than estimated.

ISSN:0003-6951    

DOI:10.1063/1.1754894

出版商:AIP    

年代:1967

数据来源: AIP

摘要:

Pronounced temperature‐dependent transfer of excitation from the Er3+laser pump levels to lower levels of Er3+was observed in CaF2:ErF3single crystals at ErF3concentrations exceeding 12.5 wt %. Transfer of excitation from Er3+to Tm3+occurred when TmF3was included as a second active constituent of the crystals. Stimulated emission of the4I11/2→4I13/2transition of Er3+at 2.69 &mgr; at 298°K resulted independently of Tm3+and as a consequence of concentration quenching of emission of Er3+from levels above4I11/2. At 100°K reduced transfer of excitation to4I11/2of Er3+occurred due to radiative emission from levels above4I11/2, and laser emission of Tm3+was detected at 1.86 &mgr;.

ISSN:0003-6951    

DOI:10.1063/1.1754895

出版商:AIP    

年代:1967

数据来源: AIP

ISSN:0003-6951    

DOI:10.1063/1.1754896

出版商:AIP    

年代:1967

数据来源: AIP