Fiber-Coupled Tapered Amplifier in a Hermetic 14-Pin Butterfly Package Emitting 3 W at 780 nm and More than 2.5 W at 850 nm

The wavelength range around 780 nm and 850 nm is extensively used for both high resolution spectroscopy and quantum technology (QT). For example, the D2 transition of cesium (Cs) and the D2 transition of rubidium (Rb) lie within these wavelength ranges. [1], [2] For compact spectrometers with high resolution and especially for QT of the second generation, compact and long-term stable systems are a prerequisite for the breakthrough of the technology. [3] In this paper we demonstrate a miniaturized fiber-coupled tapered amplifier (mini TA), which combines high output power, excellent beam properties $(\mathrm{M}^{2} < 2)$ and high coherence in 14-pin butterfly package with collimated output beam. To the best of our knowledge this is the first time demonstration of a fiber-coupled TA in this power range with a collimated output beam in a hermetically sealed package.