Frequency conversion of 946 nm lasing: efficient doubling to 473 nm and tripling to 315 nm

Summary form only given. Efficient frequency doubling and tripling of a pulsed 946-nm Nd:GYAG/Nd:YAG laser were achieved utilizing tandem pairs of beta-barium-borate (BBO) crystals. While good harmonic conversion efficiency has been demonstrated utilizing a short pulsed, seeded Ti:Al/sub 2/O/sub 3/ laser, alternate techniques are needed for systems with a long pulse length of the fundamental, and peak powers less than a MW. Tandem BBO crystals provide this alternative, with good conversion efficiency, if attention is paid to the acceptance angles and crystal separation. With two crystals used in tandem, the acceptance angles are different if one or both of the nonlinear crystals are varied. Separation of the tandem crystals is also important because of the dispersion in air. Measurements of the effects of separation agree with a model that accounts for both the phase retardation of the crystal coatings and the dispersion of air. In addition, the effects of focusing the fundamental were evaluated.