Ruining Li

Double-end-pumped 11-W Nd:YVO4 cw laser at 1342 nm

A compact, high-power, and high-stability Nd:YVO4 laser at 1342 nm has been developed. As high as 11 W cw output for 35 W of incident pump power with a slope efficiency of about 31.4% has been obtained. It has been shown that a reasonable and effective way to improve the output power is to choose a pumping scheme that can effectively extend the range of the stable resonator region by choosing the optimal dopant concentration and length of the laser rod.

High-power and high-quality, green-beam generation by employing a thermally near-unstable resonator design

We have obtained green-beam quality of M2 = 6.2 at an average output power of 120 W by intracavity frequency doubling of a diode-side-pumped, Q-switched Nd:YAG rod laser with a repetition rate of 10 kHz and an optical-to-optical conversion efficiency of 15.2%. To achieve high-beam quality at high average power, the laser employs a thermally near-unstable resonator design with two-rod birefringence compensation in an L-shaped flat-flat cavity. The output power fluctuation of the green laser remains less than 0.9% in 4 h.

Generation of 4.3-W coherent blue light by frequency-tripling of a side-pumped Nd:YAG laser in LBO crystals.

High average power nanosecond pulsed light is obtained using a compact all solid state Nd:YAG laser. The laser is operated in Q-switched mode at the 1.3 micron fundamental and internally frequency tripled using two LiB3O5 (LBO) crystals. 4.3 W average power at 440 nm was demonstrated at 3.5 kHz and a pulse width of 150+/-10 ns (FWHM). The beam quality of M2 value is 5+/-1 in both dimensions. The short-term average power stability of the light source is better than 5.6%. Spectral selecting is proposed to increase production efficiency at 440 nm.

Configuration to improve second-harmonic-generation conversion efficiency

The dependence of second-harmonic-generation (SHG) conversion efficiency on the intercrystal phase shift between two nonlinear crystals is analyzed with heuristic theory, and a novel scheme for SHG with two cascaded nonlinear crystals and a polarization modulator is proposed. More than 30 W output power is obtained experimentally at 532 nm with 70% external doubling efficiency. To the best of our knowledge, this is the highest conversion efficiency obtained with LiB3O5 crystal external frequency doubling. This scheme provides a simple and effective method for improving second-harmonic conversion efficiency.