Research on Integrated Quantum Photonic Devices

研究工作是在新型量子光子器件上进行的，该器件应用于利用光子特性的未来量子信息通信系统。主要研究结果如下：1.对二次谐波产生、和频差频产生、参量荧光等非线性光学相互作用进行了量子理论分析，计算了输出光的量子噪声和相关性，建立了器件设计方法; 2.对分布布拉格反射半导体激光器进行了量子理论分析，阐明了抑制量子噪声和压缩特性的条件; 3.建立了铌酸锂波导和准相位匹配结构的制备技术。发展了一种新的在MgO：LiNbO_3晶体中形成QPM结构的方法，即周期性紫外光照射和外加电压。4.设计并制作了LiNbO_3光波导器件原型。为了提高效率，采用反向质子交换技术掩埋波导。5.设计并制备了两种LiNbO_3波导QPM非线性光学器件，分别用于产生平行和交叉偏振的双光子，实验结果表明，器件的性能与理论预测接近，双光子的量子相关性也很好。获得了高达70%的量子效率，并实现了噪声水平低于标准量子极限0.8dB的压缩光。7.实验研究了两台低噪声DBR激光器产生量子关联孪生光束的可能性。

Research work was performed on novel quantum photonic devices for applications in future quantum information communication systems using photon properties. The obtained results are summarized as follows :1.Quantum theory analysis was performed on nonlinear-optic (NLO) interactions including second-harmonic generation (SHG), sum and difference frequency generations (SFG/DFG), parametric fluorescence (PF) to calculate quantum noises and correlations of the output beams and establish the device design techniques.2.Quantum theory analysis was performed on distributed Bragg reflector (DBR) semiconductor lasers to clarify the conditions for quantum-noise suppression and squeezing characteristics.3.Techniques for fabrication of LiNbO_3 waveguide and quasi-phase matching (QPM) structures were established. New technique using periodic ultraviolet light irradiation and voltage application was developed for formation of QPM structures in MgO:LiNbO_3 crystals.4.Prototype devices using LiNbO_3 waveguides were designed and fabricated. Waveguides were buried by reverse proton-exchange technique for efficiency enhancement. Efficiencies as high as 1400%/W were accomplished in SHG/DFG devices.5.Two types of LiNbO_3 waveguide QPM NLO devices for generation of parallel- and cross- polarized twin photons were designed and fabricated, and the performances close to the theoretical predictions and quantum correlation of the twin photons were experimentally demonstrated.6.DBR lasers for squeezed light generation were designed and fabricated. Quantum efficiencies as high as 70% was obtained, and generation of squeezed light with noise level 0.8dB below the standard quantum limit was demonstrated.7.Generation of quantum-correlated twin beams by two low-noise DBR lasers was experimentally studied, and the possibility was demonstrated.