## 1 Introduction  
The special structure of alkali metal atoms is the foundation of precision spectra, laser cooling and trapping of atoms, atom interferometers, atomic frequency standards, etc. Amongst these atoms, rubidium (Rb) and cesium (Cs) have been studied in the greatest detail. The 5S\({}_{1/2}\)-5P\({}_{3/2}\) transition (D\({}_{2}\) line) of rubidium atoms corresponds to 780 nm, and the 6S\({}_{1/2}\)-6P\({}_{3/2}\) transition (D\({}_{2}\) line) of cesium atoms corresponds to 852 nm. Therefore, the 780 nm and 852 nm lasers are important. High-power single-frequency 780 nm and 852 nm lasers can be employed for laser cooling and trapping [1; 2; 3; 4], atomic coherent control [5; 6], atomic interferometers [7; 8], and quantum frequency standards [9; 10]. In addition, 1.5 \(\upmu\)m squeezed light field and quantum-entangled light fields can be prepared from an optical parametric oscillator or optical parametric amplifier pumped by a single-frequency 780 nm laser and has important applications in continuous-variable quantum communication [11], gravitational wave detection [12] and so on. The common means to produce high-power 780 nm and 852 nm laser beams are semiconductor lasers with tapered amplifiers, a master-oscillator power amplifier (MOPA) and Ti:sapphire lasers. However, these systems can only operate in a relatively quiet and clean laboratory environment. In this context, the disadvantages of semiconductor MOPA systems and Ti:sapphire lasers, such as high cost, large size, and sensitivity to vibration and temperature fluctuations, are obvious. On the other hand, telecom-band lasers have attracted increasing attention in recent years for their extensive and important applications, such as integrated optical devices, all-optical networks, multiwavelength channels [13] and so on. The 1560 nm erbium-doped fiber laser (EDFL) and erbium-doped fiber amplifier (EDFA) are more stable and durable and have been commercialized. These systems can provide a more powerful output than solid-state lasers, and a large number of experiments have been carried out with this system. They even achieved frequency doubling at 780 nm [14] in the plane. In 2015 [15], our group also used fiber lasers and amplifiers to produce a 637.2 nm red laser from single-pass sum-frequency generation (SFG) with two infrared lasers at 1560.5 nm and 1076.9 nm in periodically poled magnesium-oxide-doped lithium niobate (PPMgO:LN) bulk crystal. Compared with the previous structures, a system that was composed of fiber lasers and amplifiers, and quasi-phase-matched (QPM) non-linear materials, is more remarkable. Therefore, it can be applied in many fields. First, a 780 nm laser can be produced from second-harmonic generation (SHG) with this system, and we have performed these experiments previously [16; 17; 18]. The 852 nm laser can be produced from SFG, and there are many research groups working on these experiments. In 2017 [19], [PERSON] et al. reported mulyi-line operation of all fiber laser system at 780 nm and 852 nm based on waveguides, and they used this system for interferometry of cesium and rubidium atoms. In 2018 [20], [PERSON] et al. demonstrated a watt-level narrow-linewidth fibered laser source at 852 nm by a periodically poled lithium niobate waveguide. The lasers are confined to a very small space in the waveguide, which makes the waveguide a good match with the lasers; however, there will be dispersion and incomplete matching in the bulk crystal. Nonetheless, the bulk crystal can hold more power input, which means that we can obtain a higher power output with a bulk crystal using a high-power injection. In our experiment, the 780 nm and 852 nm lasers are produced from single-pass SHG and SFG with the 1560 nm and 1878 nm lasers in the PPMgO:LN bulk crystal. Two fundamental lasers are boosted by the corresponding fiber amplifiers, an EDFA for the 1560 nm laser and a thulium-doped fiber amplifier (TDFA) for the 1878 nm laser. The system is particularly robust with single-pass configuration and diode-laser-seeded fiber amplifiers.