Abstract

For all-fiber setups like two-tone single frequency amplifiers [1, 2], amplifiers with auxiliary seed signals [3] or high power core-pumped amplifiers, single-mode fiber components for wavelength multiplexing are essential. The main drawback of most commercially available fused single-mode fiber couplers is that the power handling is specified only up to a few Watts [1]. In this contribution we present an in house-developed fused single mode wavelength division multiplexer (WDM) capable of multiplexing two wavelengths up to a power of 26 W without, and 16 W with integrating it in a core-pumped fiber amplifier. For the development of the high power WDM we used fiber with a core diameter of 10 µm and a numerical aperture of 0.075. The insertion loss and the isolation of the WDM were < 0.3 dB and > 17 dB. To verify the maximum power handling of the developed high power WDM in an amplifier setup, we integrated it in an all-fiber core pumped amplifier (Fig 1). The pump laser system consisted of a seed diode delivering an average power of 200 mW at a wavelength of 1025 nm, a pump combiner (6+1x1) and an Ytterbium doped double clad fiber. It delivered a maximum output power of 26 W at a wavelength of 1025 nm. The amplifier setup consisted of a seed diode with an output power of 150 mW at a wavelength of 1066 nm, two high power WDMs and a core-pumped ytterbium doped double-clad fiber with a core diameter of 10 µm (Fig. 1). A first WDM multiplexed the pump (1025nm) and the signal (1066nm) wavelength, while a second WDM served as pump and signal demultiplexer after signal amplification.

© 2011 Optical Society of America