Watt-level thulium:holmium-codoped versus holmium-doped polarization-maintaining fiber amplifier at 2050 and 2090 nm

We present the performance of a thulium:holmium-codoped fiber amplifier operating at 2050 and 2090 nm signal wavelength. This amplifier is built with polarization-maintaining fibers and is clad-pumped at 793 nm. We demonstrate more than a watt of signal power for both signal wavelengths. We compare the performance of this amplifier with a previously developed holmium-doped fiber amplifier operating at the same signal wavelengths. The amplifiers are compared in view of their optical-to-optical efficiency, optical bandwidth, gain, and noise figure.