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半波电压是电光相位调制器的一个重要指标,针对现有半波电压测量方法存在的测量误差大、测量装置复杂等问题,提出了基于激光相控阵光束扫描原理的半波电压测量方法。通过理论分析,得到了远场主光束的偏移量和相位调制器半波电压的关系表达式。搭建了1×2全光纤激光相控阵光路,对铌酸锂波导相位调制器的半波电压进行了实验测量,改变相位调制器的加载电压,记录多幅远场光强分布图,通过求平均值减小测量误差,而且根据远场光强分布的变化得到了相位调制特性曲线。结果表明,该方法测量装置简单,不仅可以精确地测量半波电压,还可以对相位调制线性度进行分析,具有重要的工程应用价值。
Half-wave voltage is an important indicator of electro-optic phase modulator. Aiming at the problems of large measurement error and complicated measuring device, the half-wave voltage measurement method based on laser phased array beam scanning is proposed. Through the theoretical analysis, the relation between the offset of the far-field main beam and the half-wave voltage of the phase modulator is obtained. A 1 × 2 all-fiber laser phased array optical path was set up to experimentally measure the half-wave voltage of the LiNbO 3 phase modulator. The voltage of the phase modulator was changed and the far-field light intensity distribution was recorded. The average value reduces the measurement error, and the phase modulation characteristic curve is obtained according to the change of the light intensity distribution in the far field. The results show that the method is simple, not only can accurately measure the half-wave voltage, but also can analyze the phase modulation linearity, which has important engineering application value.