We investigate in-band pumping of a Tm,Ho,Lu:CaGdAlO4 laser using a Raman-shifted Er-fiber laser (1678 nm), in the continuous-wave (CW) and mode-locked (ML) regimes. A maximum output power of 524 mW ...is obtained in the CW regime with a 5% output coupler at an absorbed pump power of 2.04 W, corresponding to a slope efficiency of 27.9%. A maximum CW wavelength tuning range of 160 nm at the zero level, from 1984 to 2144 nm, is obtained with a 0.2% output coupler. In the ML regime, pumping with 5.5 W (unpolarized), the average output power (0.2% output coupler) reaches 148 mW at a repetition rate of ~96 MHz. The output spectrum is centered at 2071.5 nm with a FWHM of 21.5 nm (σ-polarization). The pulse duration amounts to 218 fs (time-bandwidth product equal to 0.327).
Thermal lensing is studied in monoclinic Yb:Ca 4 YO(BO 3 ) 3 (Yb: YCOB) oxoborate crystals cut along the optical indicatrix axes. For all orientations, the thermal lens is positive. In the Z-cut ...crystal, the sensitivity factors of the thermal lens are M Z-X = 2.4 and M Z-Y = 2.8 m -1 /W (for E∥X), and the astigmatism degree is as low as S/M = 14%. The positive thermal lens in Yb:YCOB is related to the large thermal expansion and strong photoelastic effect. Microchip lasers are realized with 3-mm-long X, Y, and Z-cut 15 at.% Yb:YCOB crystals. With a Z-cut crystal, maximum output power of 8.35 W is achieved at ~1040 nm with slope efficiency of 70%. Using various crystal cuts and output coupler transmissions, multiwatt emission in the spectral range of 1033-1091 nm is demonstrated.
Zinc oxide (ZnO) nanorods (NRs) oriented along the crystallographic 001 axis are grown by the hydrothermal method on glass substrates. The ZnO NRs exhibit a broadband (1-2 µm) near-IR absorption ...ascribed to the singly charged zinc vacancy V
. The saturable absorption of the ZnO NRs is studied at ≈1 µm under picosecond excitation, revealing a low saturation intensity, ≈10 kW/cm
, and high fraction of the saturable losses. The ZnO NRs are applied as saturable absorbers in diode-pumped Yb (≈1.03 µm) and Tm (≈1.94 µm) lasers generating nanosecond pulses. The ZnO NRs grown on various optical surfaces are promising broadband saturable absorbers for nanosecond near-IR lasers in bulk and waveguide geometries.
A diode-pumped Yb:KYW planar waveguide laser, single-mode Q-switched by evanescent-field interaction with graphene, is demonstrated for the first time. Few-layer graphene grown by chemical vapor ...deposition is transferred onto the top of a guiding layer, which initiates stable Q-switched operation in a 2.4-cm-long waveguide laser operating near 1027 nm. Average output powers up to 34 mW and pulse durations as short as 349 ns are achieved. The measured output beam profile, clearly exhibiting a single mode, agrees well with the theoretically calculated mode intensity distribution inside the waveguide. As the pump power is increased, the repetition rate and pulse energy increase from 191 to 607 kHz and from 7.4 to 58.6 nJ, respectively, whereas the pulse duration decreases from 2.09 μs to 349 ns.
Mode-locked laser operation based on a single-walled carbon nanotube saturable absorber is demonstrated in the 2 μm spectral range using Tm-doped KLu(WO 4 ) 2 as active laser medium. The mode-locked ...laser delivers pulses as short as 141 fs at a center wavelength of 2037 nm. The pulse spectrum encompasses about 100 nm and the pulse duration is only 5% longer than the bandwidth limit. The oscillator operating at a repetition rate of 88 MHz delivers 26 mW average output power.
We discuss a concept for incorporating dispersion compensation into a saturable absorber mirror. This integrated device relies on an absorber layer embedded in a resonator structure and can provide ...negative dispersion of several 1000 fs 2 , similar to the spectral phase characteristics of a Gires-Tournois interferometer. A similar integration is possible also for semiconductor gain structures, as they are employed in semiconductor disk lasers. We will provide a detailed analysis of the dispersion compensation capacities of our approach, linking dispersion scaling and nonlinear properties of the device. The theoretical part will be illustrated by dispersion measurements on prototypical devices. We believe that our concept paves the way for fully integrated vertical semiconductor femtosecond lasers but may also find numerous applications in solid state lasers and femtosecond fiber lasers
We describe a compact Yb:YAG laser Q-switched by a graphene-based saturable absorber and pumped by a laser diode at 932 or 969 nm. The compact laser generates a maximum average output power value of ...185 mW at 1032 nm with a slope efficiency value of 12%. The shortest duration of the Q-switched pulse achieved is 228 ns at a repetition frequency of 285 kHz. The maximum pulse energy amounts to 0.65 μJ.
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