Monolithic edge-cladding process for the elliptical disk of N31-type Nd-doped high-power laser glass

• Published in: High power laser science and engineering Vol. 10
• Main Authors: Chen, Huiyu, Qian, Min, Chen, Youkuo, Wang, Xin, Tang, Jingping, Wen, Lei, Hu, Junjiang, Chen, Wei, Chen, Shubin, Hu, Lili
• Format: Journal Article
• Language: English
• Published: Cambridge, UK Cambridge University Press 01.01.2022
• Subjects: Adhesives; Annealing; Bond strength; Cladding; Heat; High power lasers; High temperature; Lasers; Liquid cooling; Molds; Neodymium lasers; Polymers; Radiation; Reflectance; Simulation; Spontaneous emission; Thermal stress; Wave fronts; monolithic edge-cladding process; interface bubble; stress birefringence; N31-type Nd-doped phosphate laser glass; residual reflectivity
• ISSN: 2095-4719; 2052-3289
• DOI: 10.1017/hpl.2022.5

This paper investigates the monolithic edge-cladding process for the elliptical disk of N31-type Nd-doped phosphate laser glass, which will be utilized under liquid cooling conditions for high-power laser systems. The thermal stress, interface bubbles and residual reflectivity, which are due to high-temperature casting and bonding during the monolithic edge-cladding process, are simulated and determined. The applied mould is optimized to a rectangular cavity mould, and the casting temperature is optimized to 1000°C. The resulting lower bubble density makes the mean residual reflectivity as low as 6.75 × 10−5, which is enough to suppress the amplified spontaneous emission generated in the Nd-glass disk, and the resulting maximum optical retardation is converged to 10.2–13.3 nm/cm, which is a favourable base for fine annealing to achieve the stress specification of less than or equal to 5 nm/cm. After fine annealing at the optimized 520°C, the maximum optical retardation is as low as 4.8 nm/cm, and the minimum transmitted wavefront peak-to-valley value is 0.222 wavelength (632.8 nm). An N31 elliptical disk with the size of 194 mm × 102 mm × 40 mm can be successfully cladded by the optimized monolithic edge-cladding process, whose edge-cladded disk with the size of 200 mm × 108 mm × 40 mm can achieve laser gain one-third higher than that of an N21-type disk of the same size.