INVESTIGATION OF EXCITONIC STATES CREATED BY TWO-PHOTON PAIRS IN PARAMETRIC DOWN CONVERSION.

A非线性晶体泵入激光光emits highly correlated photon pairs with parametric down conversion （PDC） processes。这些PDC光子对在一个坚实的兴奋状态中的兴奋状态是为了让正常两个光子的兴奋变得不同。我们打算用I^- ions研究在TLBr晶体中的现象。我们研究了在TlBr中发现的异常（I）在一个脉冲Ti的光子激发下：激光器（455纳米，10纳秒）在不同温度下。两个宽带发射波段观察到2.2 eV和2.45 eV。两个发射波段的衰减率在10 K以上，而那些衰减率在2K以上。通过分析它们的衰变特性，这些发射乐队被归类为外来自我欺骗的两种类型。我们测量了TLBr（I）下正常的双光子激发过程中的异常的光。使用的两个光源是：由脉冲Nd：YAG激光泵入的钛的基本原理：S激光器，以及一个模式锁定的钛：S激光器，每个脉冲宽度为10纳秒，大约100 fs，相应地。研究结果显示了光在单光子激发和双光子一下的细微差别。我们试图在PDC光的激动人心的两对闪烁的光子下观察到激动人心的发光。ML Ti的第二个谐波：S激光器被用于常规配置中的非线性晶体BBO。“被折叠的光子对被发现是如此之小，以至于我们无法观察到这种激动人心的光芒。”然后BBO水晶被Ti的第二谐波所兴奋：激光器的脉冲宽度为10纳秒。PDC的灯光似乎比ML Ti：S激光器所产生的更强。我们将调查TLBr中的激动人心的发光（I）在这个PDC灯光中充满激情的光子对下。此外，我们想提高ML Ti的输出功率：激光器。

A nonlinear crystal pumped by laser light emits highly correlated photon pairs with parametric down conversion (PDC) processes. Excitonic state in a solid excited by these PDC photon pairs is thought to be different from those excited by normal two photons. We intended to study the phenomena in TlBr crystals doped with I^- ions.・We studied photo-luminescence due to the excitons in TlBr(I) under one photon excitation by a pulse Ti:S laser (455nm, 10ns) at different temperatures. Two broad emission bands were observed at 2.2 eV and 2.45 eV. Both emission bands decayed non-exponentially above 10 K while those decayed exponentially at 2 K. Analyzing their decay properties, these emission bands are ascribed to the two types of extrinsic self-trapping of the excitons.・We measured photo-luminescence of the excitons in TlBr(I) under normal two-photon excitation process. Two light sources were used : the fundamental of a Ti:S laser pumped by a pulsed Nd:YAG laser and that of a mode-locked Ti:S laser, whose pulse widths were 10ns and about 100fs, respectively. The results show little differences in the luminescence spectra under the one-photon excitation and the two-photon one.・We tried to observe the exciton luminescence under the excitation by entangled photon pairs of PDC light. The second harmonic of the ML Ti:S laser was fed to a nonlinear crystal BBO of Type II in the collinear configuration. The down converted photon pairs were found to be so small that we could not observe the exciton luminescence. Then the BBO crystal was excited by the second harmonic of the Ti:S laser whose pulse width was 10ns. The PDC light was seen to be stronger than that induced by the ML Ti:S laser. We will investigate the exciton luminescence in TlBr(I) under the excitation by entangled photon pairs of this PDC light. In addition we want to improve the output power of the ML Ti:S laser.