The Q-Switched Mode Locking (QML) regime provides the generation of relatively high peak power picosecond pulses train with energies of a few muJ each in a simple resonator. The fully modulated efficient QML regime was demonstrated in the diode-pumped Nd:YVO4 laser. The acousto-optic cell playing a double role of Q-switch and Mode Locker was located near flat output coupler. The two folding mirrors were mounted on the translation stages for matching the resonance frequency of the cavity to the radio frequency of acousto-optic modulator. The QML pulses with envelope durations of 100-150 ns and near 100% modulation depth were observed for wide range of pump powers and repetition rates. Up to 3 W of output average power, 100 muJ of the envelope energy, having approximately 5-8 mode-locked pulses were achieved.

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6 W of output power and near 50% slope efficiency with respect to absorbed pump power was demonstrated in free-running mode for a short, 40-mm long resonator. The uncoated, with 3.5% dopant of thulium YLF rod of ⌀ 3 × 8 mm size wrapped with indium foil was mounted in copper heat-sink maintaining 293 K temperature of coolant water and inserted in a short, 40-mm long resonator. For pumping the fiber coupled (0.4 mm core diameter) laser diode bar at 792-nm wavelength was deployed. The fused silica acousto-optic modulator with above 80% diffraction efficiency for 25-W power of RF was taken as the Q-switch for such a laser. In the best case of Q-switching mode up to 2-mJ output energy with 20-ns pulse duration corresponding to 100-kW peak power was demonstrated for rep. rate of a few Hz. Emission wavelength was around 1904 nm for both free-running and Q-switching regimes.

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A tunable, lamp-pumped Cr3+:LiCaAlF6 laser that operates in the 760-800-nm wavelength range is demonstrated. As a passive Q switch the V3+:YAG crystal, characterized by wide saturable absorption in the 760-900-nm wavelength range, was applied. The V3+:YAG parameters were determined by spectroscopic and saturable transmission measurements. The 30-mJ output energy at 2-Hz repetition rate in the free-running regime was obtained in a cavity reinforced by a diaphragm near the fundamental mode. The dispersive prism inserted into the cavity enabled tuning in the 760-800-nm wavelength range. In the passive Q-switching regime we achieved greater than 1-mJ energy with 50-ns pulse duration in a 35-cm-long cavity. A numerical model that takes into account the short recovery time of V3+:YAG (approximately 5 ns) and excited-state absorption was used to analyze such a laser.