根据Anderson等近期的理论研究，简要介绍了Ⅱ类相位匹配倍频过程产生纠缠光的理论计算过程，得出了纠缠的类型、纠缠度与抽运功率的函数关系和纠缠度的理论值。利用Ⅱ类非临界相位匹配的KTP晶体作为倍频晶体，采用倍频腔结构为半整块的单端驻波腔(由于腔的入射光与反射光重合，无法直接取出纠缠光束，需要先将腔内的纠缠光束当作一对压缩的耦合模取出，再在50/50光学分束器上干涉恢复一对纠缠的本征模)，在基频光波长获得了具有正交振幅负关联、正交相位正关联特征的量子纠缠光束对，它们的正交振幅和噪声低于散粒噪声基准0.2±0.1 dB，正交相位差噪声低于散粒噪声基准1±0.2 dB。最后分析了两个正交分量的纠缠度不平衡的原因。与目前常用的光学参变振荡器相比，此类纠缠产生源的装置具有便捷和结构简单的优点。

Following Anderson's recent investigation, the theoretical description of generating entangled light through type Ⅱ phase-matched doubling process is presented. Entanglement type, entanglement rate and relation between entanglement rate and pump power are derived. The nonlinear crystal is type Ⅱ noncritical phase-matched KTP, and the resonant cavity is a monolithic, single ended, standing wave cavity. For the overlapping of the incident light and reflect light the entangled light cannot be retrieved from the cavity directly. They have to be retrieved in the form of a pair of coupled squeezed light, and then, squeezed light is interfered on a 50/50 optical beam splitter to restore the entangled light. The quantum entangled beams of subharmonic waves with anti-correlated amplitude-quadratures and correlated phase-quadratures are experimentally generated from a resonating frequency-doubler pumped by a subharmonic laser through a type-Ⅱ phase matching frequency-conversion. Noise power spectra of the amplitude sum and the phase difference between the entangled beams are 0.2±0.1 dB and 1±0.2 dB below the shot noise levels, respectively. Finally, the unequal entanglement rate of two quadrature is analyzed. Compared with the authors' frequently used method of generating entangled light——the optical parametric oscillator, the configuration of authors' system is relatively simple.