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12 October 2010 Q-switched resonantly pumped Er:YAG laser with a fiber-like geometry
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Er3+:YAG eye-safe laser emitting at 1.6 μm is an interesting source for various applications such as remote sensing, ranging, designation and free-space communications for two main reasons: its emitting wavelength lies in a region of high atmospheric transmission and high sensor sensitivity and the resonant pumping into the 4I13/2 upper laser manifold ensures highly efficient operation. The recent availability of internal grating stabilized narrow linewidth, high-power laser diodes in the 1.53 μm range, makes this laser even more appealing. The only shortcoming to be solved for a really efficient resonantly diode pumped Er3+:YAG laser is how to have a good overlap between the pump radiation and the laser cavity mode. Indeed, due to up-conversion processes among the Er3+ ions, to achieve efficient lasers it is necessary to use low doped samples. This requires the use of rods with lengths of several cm that are not compatible with the low beam quality of the diode lasers. In this work, we report on a resonantly diode pumped Q-switched Er3+:YAG laser with a crystalline fibre-like geometry emitting at 1.64 μm. In this scheme, the pump radiation is confined into a 60 mm long crystal with a diameter of 1.2 mm thanks to the multiple total internal reflections (TIR) that occur on the barrel surface, allowing efficiently pumping of such a long crystal. A maximum output power of more than 14 W in continuous wave mode and pulse energies of 8 mJ in Q-switching mode have been observed, when pumped with - 40 W of absorbed power. Even if these values are still far from the performances reported using hybrid fibre-bulk laser scheme, these results clearly show that TIR-based Er3+:YAG fibre-shaped crystalline rod laser is a promising technology for the development of efficient high-power and high-energy eye-safe laser. Finally, the effect of thermal lensing on such crystalline fibre geometry is discussed.
© (2010) COPYRIGHT Society of Photo-Optical Instrumentation Engineers (SPIE). Downloading of the abstract is permitted for personal use only.
Stefano Bigotta and Marc Eichhorn "Q-switched resonantly pumped Er:YAG laser with a fiber-like geometry", Proc. SPIE 7836, Technologies for Optical Countermeasures VII, 78360A (12 October 2010);

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