Abstract

Fiber lasers with wavelengths longer than 1.4 μm arouse great attentions due to their eye-safe atmospheric applications. In recent years, high peak power and high pulse energy thulium-doped fiber lasers (TDFLs) at 1.9-2.1 μm are useful for many scientific and technical applications, such as remote sensing, material processing, bio-medical treatment and nonlinear frequency conversion. In particular, compact fiber lasers with high beam quality at 2050 nm are highly desirable in remote sensing benefited from their low transmission loss in the atmosphere. And also, fiber lasers at 2050 nm are ideal pump sources for ZnGeP2 crystal based optical parameter oscillators with emitting wavelengths located at 3-5 μm middle infrared region [1]. A single frequency, linearly polarized master oscillator power amplifier emitting 110 ns, 1 kW peak power pulses at 2050 nm was reported in 2014 [2]. However, the output pulse energy was limited by the nonlinear effect of stimulated Brillouin scattering.

© 2015 IEEE