KLN and Zn:KLN crystal were grown by the Czochralski method along the [100] orientation. All crystals were transparent from 380 to 760nm by the ultraviolet-visible transmittance spectra of KLN and Zn:KLN crystals. Compared with KLN crystals, the transmittance of Zn:KLN increased and its absorption edge shifted to the ultraviolet band. The infrared transmittance spectra of KLN and Zn:KLN crystals were measured. The replacement of Zn2+ in the KLN crystals was analyzed. Laser lights of 420 and 405 nm were obtained through noncritical phase-matching second harmonic generation for KLN and Zn:KLN crystal, respectively. A shorter wavelength output was obtained for Zn:KLN crystal. The frequency efficiency for all crystals reached 6-7%. (C) 2003 Elsevier B.V. All rights reserved.