Studies of the optical bandwidth of a 25 W 2 mm band PM hybrid Ho-/Tm-doped fiber amplifier

New developments in LIDAR and atmospheric sensing experiments highlight the need for studies of the optical bandwidth and wavelength dependence of multi-watt, large bandwidth, high dynamic range polarization-maintaining optical amplifiers in the 2-2.1 mm band. Recently we have demonstrated a hybrid single clad-double clad Tm-doped fiber amplifier with greater than 20 W output and a dynamic range of <20 dB in the 2 mm band, and a <25W output PM hybrid HDFA/TDFA with a dynamic range of 34 dB. Both demonstrations were carried out at a single input wavelength of 2051 nm. In this paper we extend our experimental studies to the signal wavelength dependence of a PM hybrid HDFA/TDFA with a single clad Hodoped preamplifier [4-7] and a double clad Tm-doped power amplifier. We have studied the performance of the amplifier from 2004 to 2108 nm, and in this paper, we report first experimental results for this wavelength region. We find that our hybrid Ho-Tm-doped design provides a PM fiber amplifier with a combination of large output optical signal-to-noise ratio, broad operating bandwidth, and high Pout of 28.5 W at ls = 2069 nm.