Broadband fiber-optic thulium-doped amplifier for wavelengths beyond the L-band

We present preliminary characterization of an optical fiber amplifier for wavelengths beyond the L-band based on a core-pumped thulium-doped fiber developed and fabricated in-house. We explore adaptation of an existing broadband fiber-optic thulium-doped source of amplified spontaneous emission, which generates radiation in a spectral region around 2 micrometer wavelengths, for the purpose of signal amplification. The amplifier is pumped by an erbium-doped fiber laser at 1566 nm in a backward configuration with respect to the pump power. We characterize the amplifier using a narrowband input signal at 1950 nm and 1996 nm. We optimize the amplifier setup by varying the length of the active fiber and pump power. Results show that amplification of > 30 dB at 1950 nm with maximum output power similar to 300 mW is achievable with existing setups.