红宝石中聚焦高斯光束的低空间频率群速控制.ppt

红宝石中聚焦高斯光束近轴能量由类非简并二波耦合导致的群速变化 高峰，张国权，许京军 南开大学弱光非线性光子学教育部重点实验室 南开大学光子学中心 1.10.2008 报告内容 群速延迟的研究进展 红宝石中光群速减慢与相干布居数振荡 红宝石中的光群速加快 红宝石中类非简并二波耦合效应 待解决的问题 光群速研究的若干进展 L. V. Hau, S. E. Harris Z. Dutton and C. H. Behroozi. Nature, 1999,397: 594~598. A. V. Turukhin, V. S. Sudarshanam M. S. Shahriar et al. Phys. Rev. Lett., 2002, 88: 023602. C. P. Kuo, U.osterberg, C. T. Seaton, G. I. Stegeman et al. Opt. Lett., 1988, 13: 1032~1034 S. H. Lin, K. Y.Hsu, and P. Yeh. Opt. Lett., 2000, 25: 1582~1584 M. S. Bigelow, N. N. Lepeshkin, and R. W. Boyd. Phys. Rev. Lett., 2003, 90: 113903 Hui Su and Shun Lien Chuanga. APPL. PHYS. LETT. 88, 061102 2006 ……………… 红宝石中光群速减慢与相干布居数振荡 红宝石中的光群速加快 脉冲形变与晶体位置的关系 脉冲的群速延时 拍频 * Phys. Rev. Lett., Vol 90, 113903(2003) 532nm verdi-10 laser I=490mw　peak power 100mw background power f=300mm Since the reduction of the light’s group velocity to 17 m/s in 1999, a lot of works have been done. Here is some of the works of other groups. Some of results are achieved in the atom vapor under very low temperature. The first subluminal result in ruby was given in physics review letter in 2003. Matthew S. Bigelow and his group gives the result both in the theory and experiment. In the theory, the group refractive index is the function of intensity and modulation frequency. From the equation we could find that changing the pump density leads to the change of time delays. In their experiment also the self-delay of the pump beam is observed. Since the pump intensity could change the delay time, with the self delay of the pump beam, a z-scan like setup as shown above is introduced to measure the time delay by changing the positions of a ten cm ruby rod. By change the distance of the samples from the lens, we should observe the time delay change. * * * Since the reduction of the light’s group velocity to 17 m/s in 1999, a lot of works have been done. Here is some of the works of other groups. Some of results are achieved in the atom vapor under very low