Realizing the main amplification system without window glasses is important for high-power laser devices. Not only optical components and B-integration of the system are reduced, but also the output capability and beam quality of the system are improved. While the primary problem is how to maintain the cleanliness after the window glasses being removed. In response to this problem, this paper proposes a cleanness control scheme suitable for realizing the windowless operation of the main amplification system.Take one main amplification system of a high-power laser device for example, some work are conducted: integrated design of optical pipelines, introduction of air knives, and simulation analysis of airflow field and related parameters. The integrated design of the beam tubes makes the entire main amplification system to maintain a closed environment.The air knife which can generate a high-speed air curtain and block the exchange of airflow, divides the entire system into three parts: main amplifiers, beam tubes, other optical components. For each part, we use in-situ control to achieve cleanliness. To beam tubes and main amplifiers, theoretical analysis and verification of gas flow field characteristics for different process parameters are conducted. For other components, the effectiveness of air knife air curtain protection has also been experimentally studied and analyzed. Finally, it provides important guidance for realizing the remove of the window glasses of the main amplification system.
High repetition rate slab amplifier (HRRSA) is extraordinarily indispensable for the future fusion power plant, ultra-short laser, laser weapon, and so on. Thermal controlling is the decisive factor for the repetition rate and the output energy of the slab amplifier. For larger clear aperture HRRSA, flash-lamp pumped slab amplifier based on neodymium phosphate glass (Nd:glass) is chosen with the liquid cooling. The liquid coolant circulates across the Nd:glass and takes off the thermal induced in the pumping process. A novel liquid coolant (Series A) whose refractive index is the same with Nd:glass is proposed to alleviate the wavefront distortion induced by thermal. The chemical stability of the liquid coolant under high energy flash-lamp irradiation with 200 shots and under the irradiation of a 1053nm laser with 19 hours and 37 hours are experimented. The results show that the chemical stability of the liquid coolant is stable under irradiation.
The latest progress on high power laser facilities in NLHPLP was reported. Based on a high power laser prototype, damage behavior of 3ω optics was experimentally tested, and the key influencing factors contributed to laser-induced damage in optics were deeply analyzed. The latest experimental results of advanced precision measurement for optical quality applied in the high power laser facility were introduced. At last, based on the accumulated works of 3ω elements damage behavior status in our laboratory, beam expanding scheme was presented to increase the total maximum output 3ω energy properly and decrease the laser induced damage risking of ω optics simultaneously.
Neodymium phosphate glass (Nd:glass) is the typical gain medium in the large clear aperture slab amplifiers, and provide more than 99% energy of a high power laser facility. Cladding structure is employed for decreasing the amplified spontaneous emission (ASE) and parasitic oscillation (PO) which are the key limits for the gain of large clear aperture slab amplifier. Polymer cladding is generally used since it was proposed.
Polymer is an organic glue which has risk to decompose and fracture under high flash-lamp irradiation while the irradiation is a common condition in the operation of a high power laser facility. Once the polymer glue falls off, the suppression of ASE and PO of cladding structure would be damaged. In addition, the impurities existing in the glue may form the counteractive scattering sources and reduce the suppression of the cladding structure. Moreover, the decomposer of the organic glue may affect the cleanliness of the slab cavity. Thus, an inorganic edge cladding structure based on hydroxide-catalysis bonding (HCB) was proposed which can match the requirements of the cladding structure and evade the organic glue in the high flash-lamp irradiation slab cavity. An antireflective film was used as the medial material whose refractive index was matched with the cladding structure. Bonded samples were prepared based on HCB and confirmatory experiment under high flash-lamp irradiation was finished.
Strictly controlling the cleanness of transport mirror surface in high power laser system has an important significance. Removal efficiencies of dust in different sizes and on different positions of the transport mirror surface are studied, by using the air knife blowing method with different inlet pressures and installation positions. Full experiments and range analysis show that the air knife blowing method is an effective way to control the cleanness of the transport mirror surface. The removal efficiency of dust particles in different sizes and positions of the transport mirror surface is better when inlet pressure is 0.9 MPa and the air knife installation position is 3 mm. Besides that, some simulations on flow fields are conducted. The simulation results and the experimental results have a good consistency.