Fig. 1. Schematic diagram of the NOPA cavity with coherent feedback control.相干反馈操控NOPA的基本原理图

Fig. 2. Quantum correlation noises of two quadrature components for two output beams from CFC-NOPA system versus the transmissivity of CBS for idle optical field. Each dashed curve represents the value of T₂ when the quantum correlation noises of each curve is the minimum. CFC-NOPA系统输出光场正交分量之间的量子关联噪声与CBS对闲置光场的透射率之间的曲线关系, 虚线分别表示各个曲线的关联噪声值最小时T₂的取值大小

Fig. 3. Dependences of the quantum correlation noises of two quadrature components for two output beams from CFC-NOPA system on analysis frequency: (a) Transmissivity T₁ = 0.3; (b) transmissivity T₁ = 0.5; (c) transmissivity T₁ = 0.7; (d) transmissivity T₁ = 0.7, 0.8, 0.9. CFC-NOPA系统输出光场正交分量之间的量子关联噪声随分析频率的变化曲线　(a) 透射率T₁ = 0.3; (b) 透射率T₁ = 0.5; (c) 透射率T₁ = 0.7; (d)透射率T₁ = 0.7, 0.8, 0.9

Fig. 4. Quantum correlation noises of two quadrature components for two output beams from CFC-NOPA system versus transmissivity of output coupler of NOPA. The red dashed curve represents the value of when curve 1 takes the minimum. The blue dashed curves represent the critical value of when the value of curve 2 is less than the minimum value of curve 1. The green dashed curves represent the critical value of when the value of curve 3 is less than the minimum value of curve 2. CFC-NOPA系统输出光场正交分量之间的量子关联噪声随NOPA输出镜透射率的变化曲线　红色虚线表示曲线1取最小值时 的大小; 蓝色虚线表示曲线2的取值小于曲线1的最小值时 的临界值大小; 绿色虚线表示曲线3的取值小于曲线2的最小值时 的临界值

Fig. 5. Schematic diagram of experimental setup. DBS: dichroic beam splitter; HWP1-2: waveplate; PBS1-3: polarizing beam splitter; BHD1-2: balanced homodyne detectors; SA: spectrum analyzer. 实验装置示意图　DBS: 双色分束镜; HWP1-2: 波片; PBS1-3: 偏振分光棱镜; BHD1-2: 平衡零拍探测器; SA: 频谱分析仪

Fig. 6. Experimental structure of the CFC-NOPA system.CFC-NOPA系统的实验结构图

Fig. 7. Diagram of experimental measurement results: (a) The measured amplitude-sum correlation variances noise powers of the output beams; (b) the measured phase-difference correlation variances noise powers of the output beams. The measurement parameters of SA: RBW 10 kHz; VBW 100 Hz.实验测量结果图, SA: RBW 10 kHz; VBW 100 Hz　(a)正交振幅分量和的量子噪声功率; (b)正交位相分量差的量子噪声功率