NKT Photonics A/S has released a new version of its Crystal Fibre series of double-clad rod-type fibers. The DC-200-85-Yb-ROD, developed using patented air-clad technology, features low photodarkening and is used in output stages of amplifier chains for pulsed laser amplification. It has a 65-μm mode field diameter ytterbium core, and its 200-μm pump core diameter accepts light at numerical aperture values up to 0.54 for pumping at 915 to 976 nm with absorption of 30 dB/m at 976 nm. Designed for OEM use, the fibre can be used also with existing fibre amplifiers or as a replacement for traditional crystalline rods. It is available in various forms, including bare fibre, end-sealed, cleaved or end-capped.