Frequency tuning and high-efficiency extraction of second-harmonic radiation from a prism dispersion resonator of a neodymium laser

A method for the generation of the second harmonic of the neodymium laser radiation inside a resonator was developed and investigated. This method was characterized by high efficiency of extraction of the second-harmonic radiation from the resonator. The principal element was a dispersion prism which provided directional decoupling of the fundamental-frequency and the second-harmonic beams. This made it possible to extract the second-harmonic beam bypassing the mirror. The fundamental frequency could be tuned easily within the limits of the Nd³⁺ luminescence band and this resulted in automatic tuning of the second-harmonic frequency. The polarizations of the fundamental frequency and the second harmonic were matched by introducing a crystalline quartz plate into the dispersion resonator. The efficiency of conversion of the energy corresponding to the fundamental frequency into the second harmonic amounted to ~40%. Ways for increasing this conversion coefficient and for using the suggested method in the generation of higher harmonics of solid lasers were considered.