End treatment of fibers is important to assure high peak power operation. We offer the following end treatment options: Endsealing and cleaving (0 or 5 degrees angle) – the length of the endsealing (~100 µm) will not provide significant beam expansion.     Combination of endsealing and SMA-905 high power connectors.    Endcapping with 1.6 mm (diam) x 1.4 mm (length) silica blocks providing beam expansion to reduce end facet intensity and the risk of end facet damage, without compromising the high pump acceptance angle. Also, the beam expansion significantly improves the signal return loss even for a 0 degree angled facet. Comes together with SMA-905 high power connectors.       For a DC-200/41-PZ-Yb-01 with counter-progating signal+pump combiner, see aeroLASE-PA100.