激光外差干涉中声光器件非互易特性研究

Non-reciprocal characteristics of acousto-optic devices in laser heterodyne interferometer

针对声光器件存在的非互易现象导致光强衰减影响衍射效率并降低激光外差干涉效率的问题,进行了一种基于声光驱动100MHz时声光器件非互易效应对激光外差干涉影响的研究。以光束衍射实验为主体,结合光阑、TeO2晶体对声光器件非互易值进行测量,利用光功率计获得测量过程中的器件非互易数值,在不同驱动频率下分析衍射效率分布情况;并利用100MHz的声光调制器(AOM)进行激光外差干涉实验,判断声光器件非互易效应对外差中频信号的影响。实验表明,在AOM中心频率为100～105MHz情况下,利用非互易进行激光外差干涉实验,外差信号功率从+13dBm增加到+21dBm。结果表明,射频在100MHz时声光器件中存在非互易效应,利用非互易效应可有效提高激光外差干涉效率。

According to the non-redprocal phenomenon of acousto-optic devices, the light intensity attenu- ation affects diffraction efficiency and reduces the efficiency of laser heterodyne interference. A method based on acousto-optic devices at 100 MHz of laser heterodyne interferometer under the impact of non- reciprocal effect is proposed. By performing the beam diffraction experiments, the method, which com- bines an aperture and TeO2 crystal,applies optical power measurement to obtain non-reciprocal value of the device and analyzes distribution of the diffraction efficiency under different driving frequencies. A 100 MHz acousto-optic modulator （AOM） is used in laser heterodyne interferometer experiment to deter- mine the influence of non-reciprocal effect on the heterodyne IF signal. Experiments reveal that in the ca- ses of AOM center frequency at 100--105 MHz, utilizing the non-reciprocal effect the heterodyne signal power from ＋13 dBm to ＋21 dBm can be achieved,and the IF signal has 7. 69 dB gain. The RF in acousto-optic devices at 100 MHz presents the non-reciprocal effect,and the non-reciprocal effect can effectively improve the efficiency of laser heterodyne interferometer under laboratory conditions.