平衡零拍探测技术具有低噪声和高灵敏度的特性,是量子噪声谱测量的主要方法之一。采用基尔霍夫定律，设计并研究了一种具有两级放大的平衡零拍光电探测器。由两个性能匹配的光电管相减产生的光电流经过一级跨阻放大后差分输出，再经过二级差分放大电路进行放大输出。结果表明，探测器饱和功率为5 mW，信号响应带宽约140 MHz。当入射光功率为2 mW、分析频率小于30 MHz 时，探测的光学噪声功率高于探测器电子噪声10 dB 以上。在20 MHz 附近，该探测器的共模抑制比达55 dB。

With the characteristics of high sensitivity and low noise, balanced homodyne detection technique has been one of the main methods in quantum noise measurement. Based on the Kirchhoff's law, a balanced homodyne photoelectric detector with two-stage amplification is designed and studied. The differential photocurrent of two similar photodiodes is primarily amplified by a trans-impedance amplifier, and then sent into the secondary differential amplifier. Experimental results show that the saturation power of this detector is 5 mW, and the signal response bandwidth is about 140 MHz. When the input laser power is equal to 2 mW and the frequency is lower than 30 MHz, the optical shot noise is 10 dB larger than the electronic noise. Near 20 MHz, the common mode rejection ratio of the detector could reach 55 dB.