利用1.56 μm连续单频光纤激光器抽运周期极化铌酸锂晶体，通过外腔谐振增强倍频技术获得了低噪声连续单频780 nm激光。为了实现高效率倍频，理论设计了倍频腔的最佳腔镜透射率、腔长以及腔模体积等以实现谐振倍频过程中的模式匹配和阻抗匹配。在此基础上，实验获得了输出功率达1 W的连续单频780 nm激光，倍频效率达84.8%。进一步利用高精细度模式清洁器降低激光的强度噪声，实验获得了输出功率达700 mW、强度噪声在分析频率4 MHz处达到散粒噪声基准的低噪声连续单频780 nm激光。该系统的激光波长分别位于量子态传输波段与原子存储波段，可用于研究实用化量子信息处理系统。

Low noise continuous-wave single frequency 780 nm laser is generated high-efficiently by an extra-cavity-enhanced frequency doubler constructed from a periodically poled lithium niobate crystal and a linear cavity that is pumped by a continuous-wave single frequency fiber laser at 1.56 μm. Based on the design of the transmission of input coupler and the waist of cavity to optimize the mode and impedance matching of the frequency doubler, a second-harmonic laser at 780 nm is obtained experimentally with the output power of 1 W and conversion efficiency of 84.8%. Using a high fineness mode cleaner to reduce the laser intensity noise, a low noise 780 nm laser with the output power of 700 mW is achieved and intensity noise reaches the shot-noise-limit at analysis frequency of 4 MHz. The center wavelengths of the laser system at 1.56 μm and 780 nm are in the wave bands of quantum states transmission and quantum storage, respectively, so this kind of system can be employed for researches of practical quantum information processing.