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This paper presents a high pulse energy, narrow linewidth, mid-infrared (MIR) laser at 6.45 μm, based on a BaGa4Se7 (BGSe) crystal optical parametric oscillator (OPO) pumped by 1.064 μm laser. The maximum pulse energy at 6.45 μm was up to 1.23 mJ, with a pulse width of 24.3 ns and repetition rate of 10 Hz, corresponding to an optical–optical conversion efficiency of 2.1%, from pump light 1.064 μm to idler light 6.45 μm. The idler light linewidth was about 6.8 nm. Meanwhile, we accurately calculated the OPO phase-matching condition at BGSe crystal pumped by 1.064 μm laser, and a numerical simulation system was performed to analyze the input–output characteristics at 6.45 μm, as well as the effect of crystal length on the conversion efficiency. Good agreement was found between measurement and simulation. To the best of our knowledge, this is the highest pulse energy at 6.45 μm, with the narrowest linewidth for any all-solid-state MIR ns laser in BGSe-OPO pumped by simple 1.064 μm oscillator. This simple and compact 6.45 μm OPO system, with high pulse energy and narrow linewidth, can meet the requirements for tissue cutting and improve tissue ablation accuracy. [ABSTRACT FROM AUTHOR]

We present a compact high-efficiency and high-average-power diode-side-pumped Nd:YAG rod laser oscillator operated with a linearly polarized fundamental mode. The oscillator resonator is based on an L-shaped convex--convex cavity with an improved module and a dual-rod configuration for birefringence compensation. Under a pump power of 344 W, a linearly polarized average output power of 101.4 W at 1064 nm is obtained, which corresponds to an optical-to-optical conversion efficiency of 29.4%. The laser is operated at a repetition rate of 400 Hz with a beam quality factor of [M.sup.2] = 1.14. To the best of our knowledge, this is the highest optical-to-optical efficiency for a side-pumped [TEM.sub.00] Nd:YAG rod laser oscillator with a 100-W-level output ever reported. [c] 2010 Optical Society of America OCIS codes: 140.3480, 140.3530, 140.3580.

We demonstrate a high-power 556 nm yellow-green laser generated by intracavity frequency doubling of a diode side-pumped Nd:YAG laser at 1112 nm. A symmetrical L-shaped flat--flat cavity was employed to implement efficient operation of the low-gain 1112 nm transition and to achieve good power scalability. The coatings of the cavity mirrors were carefully designed to optimize the performance of the laser, and a 92 W continuous wave laser output at 1112 nm was achieved when the pumping power of the laser diodes reached 960 W. By intracavity frequency doubling of the fundamental laser in a lithium triborate crystal, the maximum power of the frequency-doubled output at 556 nm was found to be as high as 52.3 W with a pulse repetition frequency of 10kHz. This corresponds to an optical-to-optical conversion efficiency of about 5.4%. OCIS codes: 140.3480, 140.3540, 140.3580.

We have obtained green-beam quality of [M.sup.2] = 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.

Research was conducted to examine the phase transition behavior of ferroelectric BaTiO3 thin films which were fabricated on SrTiO3(001) substrate using pulsed laser deposition. High-temperature x-ray diffraction was performed in the process of heating and cooling. Results reveal that the temperature of tetragonal-to-cubic phase transition for a BaTiO3 thin films is much higher than that of BaTiO3 bulk single crystal and that the phase transition of BaTiO3 thin film takes place in a wide temperature range.