An accurate and stable method of array element tiling for high-power laser facilities

Due to laser-induced damage, the aperture of optics is one of the main factors limiting the output capability of highpower laser facilities. Because of the general difficulty in achieving large-aperture optics, an alternative solution is to tile some small-aperture ones together. We propose an accurate, stable, and automatic method of array element tiling and verify it on a double-pass 1 × 2 tiled-grating compressor in the XG-III laser facility. The test results show the accuracy and stability of the method. This research provides an efficient way to obtain large-aperture optics for high-power laser facilities.

400 μm stripe lasers for high-power fiber coupled pump modules

We present a 940 nm quasi-continuous wave semiconductor laser designed as a building block for high-power fiber coupled pump modules.The laser comprises a 400μm narrow-stripe array mounted on an aluminum nitride substrate using hard solder.The chip has been optimized for high optical power and low lateral far-field angles.Two vertical and six lateral structure variations have been investigated to determine the best achievable performance.Operating at 1 ms pulse width and a repetition rate of 10 Hz,the laser device reaches a maximum pulse power of 86 W from a 400μm aperture and more than 62%maximum conversion efficiency.Low lateral far-field angles(95%power enclosed)of11.5 and 13.5,depending on the epitaxial design,enable efficient multimode fiber coupling.The potential for highly reliable applications has been demonstrated.

Spherical distribution structure of the semiconductor laser diode stack for pumping

A semiconductor laser diode stack is used for pumping and 8 semiconductor laser diode arrays of the stack are put on a sphere,and the output of every bar is specially off-axis compressed to realize high coupling efficiency.The output beam of this semiconductor laser diode stack is shaped by a hollow duct to the laser active medium.The efficiency of the hollow light pipe,which is used for semiconductor laser diode stack coupling,is analyzed by geometric optics and ray tracing.Geometric optics analysis diagnoses the reasons for coupling loss and guides the design of the structure.Ray tracing analyzes the relation between the structural parameters and the output characteristics of this pumping system,and guides parameter optimization.Simulation and analysis results show that putting the semiconductor laser diode arrays on a spherical surface can increase coupling efficiency, reduce the optimum duct length and improve the output energy field distribution.

Diode-pumped 13 W Yb:KGW femtosecond laser

We report on a high-power diode-pumped Yb∶KG(WO_(4))_(2)(Yb:KGW) mode-locked laser with a semiconductor saturable absorber mirror(SESAM). For 32.7 W of incident pump power, we generate 261 fs pulses with the maximum average output power of up to 13.0 W and spectrum centered around 1039 nm at 68.4 MHz, corresponding to 190 n J of single pulse energy and0.72 MW of peak power. The optical-to-optical conversion efficiency is 39.8%, and the slope efficiency is 64.4%. The Yb:KGW laser exhibits a power stability better than 0.543% of the root-mean-square in 2 h.