25 W 2 um broadband polarization-maintaining hybrid Ho- and Tm-doped fiber amplifier

Novel Highly Efficient In-Band Pump Wavelengths for Medium Slope Efficiency Holmium-Doped Fiber Amplifiers

“…To our knowledge, our presentation of 1860 nm in-band pumping for a Ho-doped fiber amplifier is the first discussion of a noteworthy in-band alternative pump wavelength for this amplifier system. Previous published work has used pump wavelengths almost exclusively at or near 1940 nm [8]- [20], [29]. A high wavelength pump near 2000 nm was investigated in [15], [19] and found to yield suboptimum results.…”

“…We start our analysis by noting that in our research on HDFAs to date, we have chosen an in-band pump wavelength of 1940 nm based on a survey of the previous literature [14]- [20], [29] and also on consideration of the gain and absorption curves for the iXblue single clad Ho-doped fiber IXF-HDF-PM-8-125 [8], [14]. Figure 1 is a plot of these gain and absorption curves, where we see that the maximum absorption is 57 dB/m at 1945 nm.…”

“…Recent development of Ho-doped optical fiber amplifiers in the 2000 nm spectral region is important for many emerging applications including LIDAR, optical telecommunications, coherent lightwave systems, and spectral sensing [1]- [7]. We have previously shown that hybrid polarization maintaining (PM) Holmium-doped fiber amplifier (HDFA) architectures exhibit low noise figure (NF), high output powers, and a large operating spectral bandwidth [8]- [13]. In all these amplifiers, the HDFA is pumped at an in-band wavelength of 1940 nm which is based on a survey of the previous literature [14]- [20], [29] and also on previous technical results.…”