[en] Small-scale ripples in intense laser beams caused by intensity or phase modulations will grow fast due to self-focusing effect after passing through the nonlinear media. This lead to the change of the intensity distribution in the beam and can cause media damage by fi lamentations when the nonlinear phase retardation(B integral) reach to the restriction value which partly depends on the primary ripple level. The certain ΔB restriction of laser system was obtained by numerical simulations which were coincidence with experiments on beam propagation in a rod Nd³⁺ glass

[en] The following aspects of the Chroma I Nd glass laser system are discussed: (1) active mode locked oscillator, (2) disc amplifiers, (3) faraday rotators, (4) plasma spatial filter, (5) the triple bounce illumination system, (6) frequency doubling, and (7) output beam characterization. In addition, information on some of the advanced laser projects is given

[en] A temperature insensitive high energy Nd:YAG Q-switched laser operating over a temperature variation range of 35 °C is presented. Multi-wavelength ( λ ) laser diode (LD) stacks and a hexagon Nd:YAG slab with an effective absorption length of 46 mm are adopted to diminish the output energy fluctuation due to the temperature changing. A couple of crossed Porro prisms are used to form a folded laser cavity with polarization coupled output, and actively Q -switched operation is realized by using a KD^*P Pockels cell. Output pulse energy of about 128 mJ is obtained over the temperature range of 10–45 °C, corresponding to an optical-to-optical efficiency of 14% and a slope efficiency of 21%. The pulse duration and beam divergence are around 17 ns and 2.8 mrad respectively. (letter)

[en] A diode-end-pumped Nd:LuYAG mixed crystal laser in the 1.3 μ m spectral domain using a simple and compact two-mirror laser cavity is reported for the first time to our knowledge. In the free-running laser operation, we obtain a simultaneous dual-wavelength laser at about 1319 and 1338 nm with a maximum output power of 2.92 W and a slope efficiency of about 26.7%. By inserting an undoped YAG etalon into the laser cavity, the two 1319 and 1338 nm lasers can be operated singly with the maximum output powers of 1.36 and 1.73 W. Moreover, three simultaneous dual-wavelength lasers at 1334.67 and 1340.93 nm, 1319.15 and 1354.57 nm, and 1335.54 and 1354.94 nm can also be yielded with maximum output powers of 1.02, 0.66, and 0.47 W as well as slope efficiencies of 12.3%, 8.9%, and 6.9%, respectively. These dual-wavelength laser sources provide potential THz wave generation by beat frequency. (paper)

[en] This short paper considers the advantages and disdvantages of active element apertures in the form of disks and long rectangular cross-section slabs used in laboratories in the U.S.A. and the U.S.S.R

[en] The performance of a single-frequency Ho:YAG laser with bow-tie cavity injected by different polarized seed lasers is studied both theoretically and experimentally. With vertically polarized (s-polarized) seeding, a 9.7 mJ single-frequency laser with a pulse width of 183 ns at the repetition rate of 252 Hz is obtained. With horizontally polarized (p-polarized) seeding, an 8.8 mJ single-frequency laser with a pulse width of 220 ns at the repetition rate of 252 Hz is obtained. The laser operating in p-polarized seeding mode performs better than the one operating in s-polarized seeding because of the stable relative center frequency of the pulses (0.9 MHz in 1 h). (letter)

[en] The influence of the spectral properties of laser diode (LD) pump source, i.e. central wavelength and linewidth, on the fiber laser performances are studied. The absorption degradation ratio (ADR) is introduced and evaluated as a guide for pump selection and fiber laser design. The spectra of wavelength-locked and wavelength-unlocked LDs are measured and they are used for fiber laser amplification. The results show that the efficiency of the wavelength-locked LDs is higher than that of the wavelength-unlocked LDs at full current but the residual pump power of wavelength-locked LDs can be much higher at lower current because of the side band. (paper)

[en] We experimentally demonstrated a wavelength tunable Kerr-lens mode-locked femtosecond laser based on an Yb:CaGdAlO_4 (Yb:CGA) crystal. The Kerr-lens mode-locked wavelength tuning range was from 1043.5 to 1076 nm, as broad as 32.5 nm, by slightly tilting the end mirror. Pulses as short as 60 fs were generated at the central wavelength of 1043.8 nm with an average output power of 66 mW. By using an output coupler with 1.5% transmittance, the Kerr-lens mode-locked average output power reached 127 mW with a pulse duration of 81 fs at a central wavelength of 1049.5 nm. (letter)

[en] During the past year design of the Nova laser has undergone significant change as a result of developments in our laser glass and optical coating evaluation programs. Two notable aspects of the glass development program deserve emphasis. First, vendor qualification for production of fluorophosphate laser glass is progressing satisfactorily. There is a reasonable expectation that vendors can meet fluorophosphate glass specifications within Nova schedule constraints. Secondly, recent gain saturation measurements have shown that the saturation fluence of the fluorophosphate glass is larger than previously supposed (approx. 5.5 J/cm²) and in fact is somewhat larger than Shiva silicate glasses. Hence, performance of Nova for pulses in the 3 ns and longer range should be satisfactory. For pulses in the 1 ns regime, of course, the fluorophosphate chain will have superior performance to that of silicate because of its low nonlinear index of refraction (approx. 30% that of silicate). These and other considerations have led us to choose a chain design based upon the use of fluorophosphate glass in our amplifiers

[en] We demonstrate a high power quasi-continuous-wave (QCW) diode-pumped Yb:YAG ceramic slab laser. The wavefront distortion of the assembled large-sized Yb:YAG ceramic slab module is evaluated firstly. Through a short cavity setup, the average output power of a single ceramic slab laser oscillator is up to 6.2 kW. The corresponding optical-to-optical efficiency with respect to the absorbed pump power is 64.8% and a slope efficiency of 72.1%, operating at a pulse duration of 560 μs and a repetition rate of 160 Hz. To the best of our knowledge, this represents a highest output power for a QCW Yb:YAG ceramic single slab laser oscillator ever reported to date. This result proves the way to the further development of high power solid-state Yb:YAG ceramic slab laser. (paper)