Abstract: The specification and drawings present an apparatus and a method for intra-cavity harmonic generation in lasers such as solid-state lasers using a multi-resonance cavity with meniscus lenses for focusing corresponding wavelength radiation components on non-linear optical elements such as non-linear optical crystals using type I or type II phase-matching for significantly increasing efficiency of the harmonic conversion and output powers of generated harmonics. Using only type I or only type II phase-matching for all non-linear crystals may eliminate the requirement of linear-polarization on the fundamental laser wavelength generation. For example, a highly efficient UV Nd:YAG laser at 355 nm (a third harmonic of the fundamental wavelength of 1064 nm for the Nd:YAG laser) using intra-cavity triple resonance cavity and meniscus lenses has been developed using embodiments described herein.

Abstract: Methods and apparatus for side pumping lasers are disclosed. By pre-collimating radiation emitted by laser diode arrays, the present invention provides transverse mode matching to achieve fundamental, or TEM.sub.00, mode operation in the corresponding (nominally vertical) axis. Optics associated with the resonant cavity additionally redirect energy longitudinally through the gain media, enhancing fundamental mode operation in the (nominally horizontal) other axis as well. With dual forty-watt linear arrays of laser diodes and four longitudinal passes, TEM.sub.00 mode outputs exceeding fifteen watts have been achieved.