Protorefractive Effect in GaP

本研究的目的是测量我们首次发现的光折变效应的GaP的基本性质。在室温下测量了其光折变增益系数和时间常数。我们使用了633nm He-Ne激光器和806nm激光二极管。结果表明，GaP可以在比GaAs和InP更短的波长下使用，并且其光折变特性与GaAs和InP相似。实验结果与假设单载流子和单阱的标准理论一致。进一步测量了不同温度下的光折变特性。在150K左右，观察到不同寻常的光折变增益行为，在几乎相同的温度下也检测到光致变色效应。这些影响是由在低温下起作用的浅层圈闭引起的。这些实验对研究深阱水平是有用的。作为应用，我们演示了利用简并四波混频产生相位共轭波。获得了0.3%的反射率。虽然反射率较低，但响应时间比铁电材料短得多。

The purpose of this research is to measure the fundamental properties of GaP whose photorefractive effect was first discovered by us. We measured its photorefractive gain coefficient and time constant at room temperature. We used both a 633nm He-Ne laser and a 806nm laser diode. It was found that GaP could be used at shorter wavelengths than GaAs and InP, and that the photorefractive properties were similar to theirs. The experimental results agreed with the standard theory in which single carrier and single trap were assumed. Further we measured photorefractive properties at various temperatures. At about 150K, extraordinary behavior in photorefractive gain was observed and at almost the same temperature the photochromic effect was also detected. These effects are caused by the shallow traps which become effective at low temperatures. These experiments will be useful for investigating deep trap levels. As applications, we demonstrated the generation of phase conjugate wave using degenerate four wave mixing. The reflectivity of 0.3 % was obtained. Although the reflectivity is low, the response time is much shorter than the ferroelectric materials.