To develop measurement technique of temporal width for femtosecond laser pulses in the short wavelength region by means of luminescence correlation method

1.用Nd：YAG锁模激光器的三次谐波脉冲（输出功率500 - 600 mW）同步泵浦染料激光器（Ancante 76 s，输出功率25 W）。用二苯乙烯3染料，我们获得了100- 1 50 mW的输出功率的脉冲在波长范围从4 - 10到460 nm。我们还试图通过在染料激光器中插入可饱和的二极管来缩短脉冲。用高保真、快速扫描的Kfichelson干涉仪和BBO晶体，用二次谐波自相关法测得脉冲的时间宽度为1.4ps。用NK 557（Nihon Kanko Shildso）或Coumarin 7，可得到脉宽小于lps的脉冲，输出功率约为1/3。然而，我们发现，不仅长时间的稳定性较差，而且脉冲之间的强度波动以及脉冲的空间波动也不可忽略。2我们构造了高保真、快速扫描的Nfichelson干涉仪。该干涉仪具有足够的精度，使我们能够测量两束激光之间的干涉图案，这是通过使用来自Ar离子激光泵浦的罗丹明6 G染料激光器的飞秒激光脉冲的测试证实的。3我们还尝试通过发光相关方法测量自相关轨迹。使用的Swuples是分子束外延生长的ZnSe和散装CdS晶体。在每个样品中，我们证实了发光自相关迹线显示出与二次谐波产生自相关迹线相似的形状。然而，由于激光脉冲的稳定性较差，两者之间的比较和详细讨论的结果并不准确。我们可以说，发光补偿法至少给出了脉冲宽度的测量，因而可以应用于BBO等非线性晶体不能使用的短波长范围内的测量。

1 We tasted a dye laser synchronously pumped by the third harmonic pulses (output power of 5OO-6OOmW) of a mode-locked cw ND-YAG laser (Antares 76s, output power of 25W). By using Stilbene 3 dye, we obtained pulses with 100- I 5OmW output power in the wavelength range from 4 10 to 460 nm. We also tried to shorten the pulses by insertingsaturableabsorberinthedyelaser. Temporalwidthofthepulsesarefoundtobel-1.4pswhichare measured by 2nd harmonic-generafion autocorrelation method using high fidelity, rapid-scanning Kfichelson interferometer equipped with BBO crystal. By using NK557 (Nihon Kanko Shildso) or Coumarin 7, pulses with the width less than lps with the output power reduced to about 1/3 are obtained. It was found, however, that not only the long-time stability is worse but also pulse-to-pulse intensity fluctuation as well as spatial fluctuafion of the pulses is not negligibly small.2 We constructed high fidelity, rapid-scanning-Nfichelson interferometer. This interferometer has enough precision that enable us to measure interference pattem between the two laser beams, which is confirmed by the test using femtosecond laser pulses from Ar ion laser pumped Rhodamine 6G dye laser.3 We also tried to measure autocorrelation traces by luminescence correlation method. Swuples used are molecular beam epitaxially-grown ZnSe and bulk CdS crystals. In each samples, we confirmed that the luminescence autocorrelation traces show the similar shape as 2nd harmonic generation autocorrelation traces. However, the results are not so accurate to compare between those two and to discuss in detail, because of the inferior stability of the laser pulses. Wecansaythattheluminescencecoffelationmethod, atleast, givesthemeasureofthepulsewidth, andthus can be applied to the measurements in the short-wavelength range where nonlinear crystals such as BBO can not be used.