双光束干涉中偏振态分布的演示实验

EXPERIMENTAL DEMONSTRATION OF THE POLARIZATION DISTRIBUTION IN DOUBLE-BEAM INTERFERENCE

光的干涉现象是波动过程的基本特征之一,是波动光学研究的主要内容.相干条件说明光波的偏振态对光的干涉效应有影响.为了让学生更好地理解光的干涉过程中偏振态的影响,本文设计了一种全息记录光路,利用一种对激发光偏振态敏感的偶氮染料样品,演示了样品经过不同偏振的两束特定波长写入激光作用后,可以观察到写入光和探测光的衍射现象.这些衍射现象说明样品中可以形成的不同类型的折射率光栅,而这些折射率光栅来源于样品表面不同偏振态的周期分布导致的染料分子的周期取向分布,从而形象地说明了光的干涉过程中相位差的重要性,有助于学生对光的干涉的深入理解.

Interference is an interesting phenomenon in wave optics. The polarization state of the light beam plays important role in the interference phenomenon. In order to let students have a better understanding of the influence of polarization distribution on the interference process, this paper designs a type of holographic recording light path. Making use of a kind of azo-dye sample, which is sensitive to the excited light polarization state, we demonstrated the double-beam interference. The diffraction of the writing beam and reading beam shows the ex- istence of refractive index grating in the sample. And the refractive index gratings come from the distribution of the re-orientation of the azo-dye molecules on the sample surface, which is resulted from the different polarization distribution of the laser. Our experiments vividly illus- trate the importance of the phase difference during the process of interference of light, which is helpful for the students to understand the polarization distribution in double-beam interfer- ence.