• Umnikov, Andrey
• Ramírez Martínez, Norberto Javier
• Barua, P.
• Sahu, Jayanta Kumar
• Núñez-Velázquez, Martin Miguel Angel

Abstract

With ytterbium doped fiber (YDF) lasers and amplifiers have reached continuous wave output power of multi-kW with direct diode pumping [1] and 10kW with tandem pumping [2] in a good beam quality, today fiber lasers are becoming the laser choice for many industrial applications and processes, defense, and scientific research. One of the challenges of high average power fiber laser is to maintain a long-term stability of the output power. In particular, photodarkening (PD) is seen as a power loss in YDF gain medium that can significantly influence the operation lifetime of the device. Moreover, it was observed that the PD is related to the transverse mode instability (TMI) that can limit the output power of the laser [3]. Here we report an efficient Yb-PS high power laser fiber fabricated using an optimized MCVD (modified chemical vapor deposition) and all-vapor -phase chelate precursor doping technique. Double -clad fi ber with a 150µm quasi-octagonal inner cladding and a 12i.tm core diameter was drawn with a low index polymer outer cladding. The core NA was 0.1, Fig.1 (a). The small signal absorption at the pump wavelength of -976nm was measured as 2.5 dB/m. Initially the fiber was tested in a 4%-4% laser cavity. An output power of >100W (limited by the available pump power) and the slope efficiency of >85% were obtained. The laser emission was centered at 1066nm.

Topics

• impedance spectroscopy
• polymer
• phase
• chemical vapor deposition
• Ytterbium