Pan Xinjian, Cai Yi, Zeng Xuanke, Lu Xiaowei, Zhang Dongping, Li Jingzhen, Chen Hongyi, Xu Shixiang
Opt Lett. 2014 Jul 1;39(13):3778-81. doi: 10.1364/OL.39.003778.
We present a modified THz electro-optic sampling method to combine the advantages of its two traditional counterparts at near 0° and 45° optical biases: excellent ability to cancel the background noises, high optical modulation, and large dynamical range. The first advantage results from the method's symmetrical layout to get dynamical noise cancellation. By setting the static birefringent phases of the two balanced beams with a pair of opposite numbers, our setup can record THz waveforms without distortion with its maximal modulation depth, thus optimal signal-to-noise ratio (SNR). The setting also releases the linearity of the measured signal from the static birefringence, thus enlarging greatly the linear dynamical range. For a given THz field, the recorded SNR with our setup, without a lock-in, is more than 10 times higher than that with the "crossed and balanced" design [IEEE Trans. Microwave Theory Tech. 47, 2644 (1999)].
我们提出了一种改进的太赫兹电光采样方法，以结合其在接近0°和45°光学偏置下的两种传统对应方法的优点：出色的背景噪声消除能力、高光调制和大动态范围。第一个优点源于该方法的对称布局以实现动态噪声消除。通过用一对相反数设置两个平衡光束的静态双折射相位，我们的装置可以在不失真的情况下以其最大调制深度记录太赫兹波形，从而获得最佳信噪比（SNR）。该设置还消除了静态双折射对测量信号线性度的影响，从而大大扩大了线性动态范围。对于给定的太赫兹场，我们的装置在不使用锁相放大器的情况下记录的SNR比“交叉平衡”设计[《IEEE微波理论与技术汇刊》47, 2644 (1999)]高出10倍以上。
