Key points are not available for this paper at this time.
We report pulse energy of 1.6 mJ at 1 kHz repetition rate from a single-frequency fiber amplifier with high energy gain of 19 dB at 1560 nm, using a 2.4 m long, Very-Large Mode Area (VLMA) Polarization-Maintaining (PM) erbium-doped fiber with 50 μm core diameter and absorption of 50 dB/m, core-pumped with a CW, 1480 nm Raman fiber laser. The in-pulse power fraction was 85%. The FWHM of the output pulses was 1.48 μs at 1 kHz repetition rate. At 150 Hz repetition rate, of interest in coherent wind LIDAR systems, we report 1 mJ, with energy gain of 17 dB, in-pulse power fraction of 72%, and FWHM of 1.24 μs. Stimulated Brillouin scattering limited the maximum energy reported here. The output of the fiber amplifier was diffraction limited, with mean beam quality factor, M2, of 1.04. The polarization extinction ratio exceeded 20 dB.
Sudarshanam et al. (Tue,) studied this question.