采用全量子理论对单块非平面环形腔Nd:YAG激光器的强度噪声特性进行了研究，通过理论分析和仿真发现，单块非平面环形腔激光器的弛豫振荡主要由真空起伏、偶极起伏和内腔损耗引起，抽运噪声和自发辐射对弛豫振荡的影响相对较小。同时，从理论上对强度噪声的光电负反馈抑制进行了分析和仿真，为实验上噪声抑制电路的设计提供了一定的理论基础。参考此理论电路，设计了可以获得较好的相位超前和低噪声宽带宽增益放大的噪声抑制电路，在实验上获得了良好的噪声抑制效果。当弛豫振荡峰为311 kHz时，弛豫振荡峰处的强度噪声被抑制了39 dB，在整个频谱范围内获得了低于-115 dB/Hz的噪声水平。

The intensity noise properties of the monolithic Nd:YAG nonplanar ring oscillator are investigated via full quantum theory. By theoretical analysis and simulation, it is obtained that the relaxation oscillation is influenced mainly by the vacuum fluctuation, dipole fluctuation and cavity loss. The influence from the pump noise and spontaneous emission noise is relatively small. Meanwhile, the optoelectronic negative feedback of intensity noise is theoretically analyzed, which can provide a theoretical basis for the design of the noise suppression circuit. Based on this theory, the noise suppression circuit is designed which has better phase advance, low noise, wide bandwidth and adequate gain. Experimentally, a satisfied noise suppression result is achieved. For the noise with a relaxation oscillation frequency of 311 kHz, the experimental result shows that the relaxation oscillation noise peak value is reduced about 39 dB, and the intensity noise level is lower than -115 dB/Hz in the entire spectrum.