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We report an efficient continuous-wave (CW) yellow beam based on a Nd:YVO4 laser with a dual-wavelength wave plate, which is a full-wave plate at 1342 nm and a quarter-wave plate at 1064 nm. By inserting the dual-wavelength wave plate into the laser cavity and tuning the fast axis angle, based on the polarized property emission of Nd:YVO4, two simultaneous wavelengths of 1064 nm and 1342 nm were achieved. A LiB3O5 (LBO) crystal that is cut for critical type I phase matching at room temperature is used for summing frequency generation (SFG) of the laser. At an incident pump power of 5 W, a maximum CW output of 224 mW was obtained for a yellow laser with a wavelength of 593.5 nm and an optical-to-optical efficiency of 4.48%. To the best of our knowledge, this is the first time that a dual-wavelength wave plate has been used to realize a Nd:YVO4 yellow laser output.

To overcome the main drawback of poor pump absorption of Nd : YVO4 lasers in-band pumped at 914 nm, three possible methods of higher temperature, longer crystal length and higher doping concentration were experimentally studied. A Nd : YVO4 laser operating at 914 nm was used as high beam quality, narrow line-width pump source to make the measurement of pump absorption accurate. Four different Nd : YVO4 crystals were used as gain mediums to investigate the effects of crystal parameters. We found that heating the crystal effects differently on output power and overall efficiency when crystal doping concentration changed. To improve the pump absorption and meanwhile achieve high efficiency, longer crystal with proper doping concentration and pump feedback should be adopted instead of highly doped crystal.

This work demonstrates a tunable continuous-wave (CW) all-solid-state orange-red source based on sum-frequency generation (SFG), using a tunable 1.4?1.5??m signal and a 1064?nm pump of an intra-cavity periodically poled LiNbO3 optical parametric oscillator in a BBO (?-BaB2O4) crystal. Elaborate intra-cavity design ensured efficient CW singly resonant optical parametric oscillator (SRO) operation. Intra-cavity SFG made full use of the high circulating pump and signal power of the SRO under an external laser diode (LD) pump power that was ten times higher than the SRO threshold. The output wavelength tuning range was 605?623?nm. The maximum output power was 370?mW at 622.8?nm with 17.1?W LD pump power, corresponding to an overall conversion efficiency of 2.2%.