We report a low-cost hybrid Yb-fiber and three-stage Yb:YAG thin-rod MOPA laser pumped by high-brightness LDs, which delivers 100.4 W average power, 7 ps pulses at 20 MHz repetition rate. The all-fiber frontend emits 17 ps, 20 MHz linearly polarized pulses with an average power of 1.5 W. The first stage Yb:YAG thin-rod amplifier is a doublepass amplifier with single end pump. The maximum output power of 20 W was obtained with respect to a pump power of 123 W. The M2 measured at 17 W output was 1.39. The second stage is bi-directionally end pumped and the maximum output power was 55.1 W under 112 W and 113 W pump powers in both directions. The slope efficiency is 20%. In the third stage, the signal was single passed and the maximum output power was 100.4 W under 113 W and 120 W pump powers in both directions. The corresponding slope efficiency is 23.4%. The pulse duration was measured to be 7 ps and the optical spectrum is centered at 1032.3 nm with 0.22 nm full-width at half maximum. The M2 measured at 91 W was 4.0.
We report a high-power chirped pulse amplification (CPA) based on nonlinear amplifying loop mirror (NALM) oscillator and Yb-doped rod-type photonic crystal fiber (PCF). An all-polarization-maintaining NALM mode-locked fiber oscillator was used providing an average power of 9.4 mW, a pulse duration of 5.3 ps at the repetition rate of 21 MHz. After pulse stretching, selection and amplification, an average power of 120 W with the pulse duration of 145 ps at repetition rate of 4.2 MHz has been achieved. The pulse duration is compressed to 14 ps using a pair of reflective gratings coated by gold film. In order to prevent the damage of the gratings, the compressed average power is limited to 51 W. The compressed pulse average power can be further improved by using transmissive gratings coated by dielectric film.
We report a tunable CW dual-wavelength Cr:ZnSe laser with collinear output pumped by a thulium doped fiber laser. By using birefringent plates, we obtained stable dual-wavelength operation between 2365 nm and 2492 nm. The maximum wavelength separation was 127 nm corresponding to a frequency offset of 6.46 THz.
We demonstrate an all fiber mode-locked ultrafast erbium laser oscillator by means of nonlinear polarization evolution (NPE) in polarization maintaining (PM) fibers. Here, the artificial saturable absorber (SA) is formed by a piece of PM active fiber and a Faraday mirror (FM). High repetition rate could be obtained thanks to the introduction of the PM active fiber. The transmission characteristics of the SA are studied through theoretical analyses as well as experimental demonstration. Channeled spectra caused by soliton-soliton interaction and birefringence-induced filter are also studied and discussed. A good agreement is achieved between the theoretical analyses and experimental results.
We report self-starting femtosecond operation of a 127-MHz SESAM mode locked Cr:ZnSe laser around 2420 nm. A thulium doped double clad fiber laser at 1908 nm was used as the pumping source. In the normal dispersion regime, stable pulse pairs with constant phase differences in the multipulse regime were observed. The maximum output power was 342 mW with respect to incident pump power of 4.8 W and the corresponding slope efficiency was 10.4%. By inserting a piece of sapphire plate, dispersion compensation was achieved and the intra-cavity dispersion was moved to the anomalous regime. A maximum output power of 403 mW was obtained and the corresponding slope efficiency was 12.2%. Pulse width was measured to be 408 fs by a collinear autocorrelator using two-photon absorption in an InGaAs photodiode. The laser spectrum in multipulse operation showed a clear periodic modulation.
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