We present results on the amplifier performance and characteristics of Yb-doped Single Mode fiber amplifiers spanning a broad range of wavelengths from 1028 nm to 1100 nm. Both PM and non-PM amplifiers are discussed, with emphasis on the use of polarization controllers in intrinsically non-PM amplifiers to obtain high Polarization Extinction Ratios (PER). In general, outside the 1064nm region, there has been relatively little discussion or work towards developing high power fiber amplifiers for operation at either 1030 nm or 1100 nm with narrow line-width and high brightness, primarily due to amplifier design and architecture issues related to strong re-absorption and amplified spontaneous emission. Here we address key fiber and amplifier design characteristics aimed at mitigating these issues while highlighting performance attributes and challenges for operation near either end of the above defined spectral range.
Beam combining of fiber lasers has attracted much interest as a practical means to power scale fiber laser/amplifiers
beyond the limitations of a single mode output from an individual fiber . Almost all of the high power demonstrations
to date that deliver good beam quality after the combing process (coherent and spectral) require some linewidth control
for efficient combining, typically less than 10GHz [2,3,4]. Previously we demonstrated single mode, Yb-doped LMA
fiber amplifiers operated with around 7GHz linewidth at 1kW output power . In this paper, the latest generations of
these amplifiers, based on the latest developments in LMA Yb-doped fiber technology demonstrate the capability to
operate with linewidths around 3GHz at the 1kW power level. We present the latest data on optical properties of these
new Yb-doped amplifiers and the SBS threshold as a function of input seed laser linewidth and discuss the technologies
being developed to operate at higher power levels and narrower linewidths.
Progress is being made developing monolithic, all-fiber 2μm wavelength devices that operate robustly at higher power
levels. This development includes the critical Tm-doped LMA fiber technology, compatible components such as pump
combiners and couplers, along with the optimization of high brightness, high efficiency 790nm pump diodes. In this
paper we present recent CW power scaling results and demonstrate a monolithic MOPA system operating at 400W
output power with around 20% E-O efficiency.
Conference Committee Involvement (2)
Laser Technology for Defense and Security VIII
23 April 2012 | Baltimore, Maryland, United States