Basic research on optical distributor using orthogonally polarized four wave mixing

时间响应是光信号分配器的基本和重要特性之一。本研究对光信号分配器的正交偏振泵浦四波混频(OPPFWM)的响应进行了深入的研究：在第一年(FY2000)，我们发现一些BaTiO_3晶体出现了OPPFWM分配器的衍射效率在光栅擦除周期的前几秒内增加的反常现象。通过理论分析和实验发现，当正负电荷载流子同时存在时，与二次载流子相比，一次载流子具有较长的时间常数。在第二年(2001财年)，我们研究了两种情况：一次和二次光栅是同相的和完全不同相的。我们发现，在异相情况下，栅擦除速度要比其他情况快得多。此外，我们还提出了一种新的方法，通过在晶体上施加外加电场来切换分配器，破坏四波混频的位相匹配，而不擦除光栅。综上所述，我们对OPPFWM的基本性质，特别是对光信号分配器的时间行为进行了研究，得到了一些有用的结果。

The temporal response is one of basic and important properties of optical signal distributor. The response of orthogonally polarized pump four wave mixing (OPPFWM) for optical signal distributor investigated intensively by this research :In the first year (FY2000), we discovered some BaTiO_3 crystals exhibit an anomalous phenomena that the diffraction efficiency of OPPFWM distributor increases for a first few seconds of grating erasure period. We showed, through theoretical analysis and experiment, the phenomena happens when both negative and positive charge carriers with different time constants exist and primary charge carrier has longer time constant, comparing to secondary charge carrier.In the second year (FY2001), we studied in the two cases : Primary and secondary gratings are in phase and they are totally out of phase. We showed in the out of phase case the grating erasure is much faster than the other. In addition to it, we proposed a novel way for switching the distributor by applying external electric field to the crystal and destroy the phase-matching of the four wave mixing, without erasing the gratings. By this way, it is possible that the switching time becomes shorter by several orders of magnitudes.In conclusion, we have obtained useful results on basic properties of OPPFWM, especially on its temporal behavior for optical signal distributors.