Waterproof coatings for high-power laser cavities

Xinbin Cheng; Siyu Dong; Song Zhi; Sebastian Paschel; Istvan Balasa; Detlev Ristau; Zhanshan Wang

doi:10.1038/s41377-018-0118-6

Waterproof coatings for high-power laser cavities

Light Sci Appl. 2019 Jan 23:8:12. doi: 10.1038/s41377-018-0118-6. eCollection 2019.

Authors

Xinbin Cheng^{1

2

3}, Siyu Dong^{1

2}, Song Zhi^{1

2}, Sebastian Paschel⁴, Istvan Balasa⁴, Detlev Ristau⁴, Zhanshan Wang^{1

2

3}

Affiliations

¹ MOE Key Laboratory of Advanced Micro-Structured Materials, Shanghai, 200092 China.
² 2Institute of Precision Optical Engineering, School of Physics Science and Engineering, Tongji University, Shanghai, 200092 China.
³ 3IFSA Collaborative Innovation Center, Shanghai Jiao Tong University, Shanghai, 200240 China.
⁴ 4Laser Zentrum Hannover e.V., Laser Components Department, Hannover, 30419 Germany.

Abstract

With the ever-increasing laser power and repetition rate, thermal control of laser media is becoming increasingly important. Except for widely used air cooling or a bonded heat sink, water cooling of a laser medium is more effective in removing waste heat. However, how to protect deliquescent laser media from water erosion is a challenging issue. Here, novel waterproof coatings were proposed to shield Nd:Glass from water erosion. After clarifying the dependence of the waterproof property of single layers on their microstructures and pore characteristics, nanocomposites that dope SiO₂ in HfO₂ were synthesized using an ion-assisted co-evaporation process to solve the issue of a lack of a high-index material that simultaneously has a dense amorphous microstructure and wide bandgap. Hf_0.7Si_0.3O₂/SiO₂ multifunctional coatings were finally shown to possess an excellent waterproof property, high laser-induced damage threshold (LIDT) and good spectral performance, which can be used as the enabling components for thermal control in high-power laser cavities.