Manufactured by NKT Photonics A/S, the DC-200-40-PZ-YB-03 is a rare-earth-doped ytterbium fiber. The patented polarizing double-clad fiber with coil control features a mode area of more than 650 μm2 while maintaining single-mode beam quality. Because it is polarizing, it delivers an improved polarization extinction ratio compared with polarization-maintaining fibers, according to the company. The multimode pump light is guided by proprietary air-clad technology, ensuring low loss, a high damage threshold and a large numerical aperture that relaxes tolerances on coupling optics and facilitates the use of lower brightness diodes. Used by industrial fiber laser manufacturers, it is available with sealed ends or with end caps and high-power SMA connectors in the company’s aeroGain Flex range.