Efficient intracavity second harmonic generation in semiconductor-pumped miniature solid-state lasers

Theoretical and experimental investigations were made of intracavity second harmonic generation (SHG) using radiation from semiconductor-pumped cw solid-state lasers. When YAG:Nd³⁺ was pumped by radiation from arrays of light-emitting diodes, the cw single-mode output power at λ = 1.06 and 1.32 µ was 120 and 100 mW, respectively, and the radiation power at λ = 0.53 µ was 30 mW. The experimental results were in good agreement with the calculations. The maximum multimode powers at λ = 1.06 and 0.53 µ were 220 and 50 mW. An analysis was made of the results of a study of SHG of radiation from a lithium neodymium tetraphosphate laser pumped by a single injection laser. It was found that intracavity SHG in semiconductor-pumped lasers can improve the efficiency by one or two orders of magnitude, can reduce the mass, size, and specific consumption of materials, and can substantially increase the useful life of lasers emitting in the green part of the spectrum.