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

Abstract

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.

Influence of Mixed Na2O/K2O on Chemical Durability and Spectral Properties of P2O5-Al2O3-BaO-K2O-Na2O-Nd2O3 Phosphate Glasses

“…Nd-doped phosphate glass has become the preferred laser gain medium for large-scale high-power laser systems due to its advantages such as moderate phonon energy, high solubility of rare earth ions, good spectral performance, small nonlinear coefficient, large stimulated emission cross-section, and facile large-scale preparation [ 1 , 2 , 3 ]. Typical representatives of commercial neodymium glass are the LHG-8 of Hoya company [ 4 ], LG-770 of Schott company [ 5 ], and N31 neodymium glass of Shanghai Institute of Optics and precision machinery, Chinese Academy of Sciences [ 6 , 7 ]. Generally, neodymium glass consists mainly of (58-62) P 2 O 5 -(8-12) Al 2 O 3 -(12-16) M 2 O-(8-12) MO-(1-2) Nd 2 O 3 .…”