We report on the experimental results of a continuously diode-laser pumped Nd:YAG laser, operating at 1064 nm and repetitively Q-switched by a Cr 4+ :YAG solid-state saturable absorber. End-pumping the Nd:YAG with a 10-W fiber-coupled diode-laser we could either optimize the energy or the average output power, depending on the choice of the saturable absorber and the output coupler. The maximum energy was 200 J in single TEM00, 17 ns pulses at 6 kHz, whereas a maximum average power of 2 W with 32-ns pulses at 20 kHz was obtained. We also present preliminary results of a repetitively Qswitched Nd:YVO4 laser at 1064 nm. The repetitive Q-switching operation is described by an improved model, which accounts for the behavior of both the active medium and the solid-state saturable absorber. The results of the model agree fairly well with the experimental data. Experimental results of second harmonic conversion are also reported and interpreted using a depleted pump model.

We employ AgGaSe(2) for difference-frequency generation between signal and idler of synchronously-pumped picosecond / femtosecond OPOs at 80 / 53 MHz. Continuous tuning in the picosecond regime is achieved from 5 to 18 µm with average power of 140 mW at 6 µm. In the femtosecond regime the tunability extends from 5 to 17 µm with average power of 69 mW at 6 µm. Maximum single pulse energies of >1 nJ in both cases represent the highest values at such high repetition rates.

The application of single-walled carbon nanotubes (SWCNTs) as saturable absorbers (SA) in a Nd:glass femtosecond laser is verifi ed as a promising alternative to traditional semiconductor saturable-absorber mirrors (SESAMs). The shortest laser pulses achieved with a SWCNT-SA fabricated by the slow-evaporation method are reported herein. Nearly Fourier-limited 288 fs pulses are obtained with negative-dispersion soliton mode-locking. The importance of the properties of the starting material, such as the degree of purity and the chirality, and the successive slow-evaporation deposition method is proven by using a multitechnique approach based on X-ray diffractometry, scanning electron microscopy, and μ -Raman spectroscopy. The high degree of nanotube alignment on the glass substrate and also the slight metallic character due to electron transfer between the glass matrix and the nanotubes themselves are identifi ed as the main features responsible for the good laser response.

We demonstrate clear inhomogeneous linewidth broadening for the disordered laser crystal Nd:BaLaGa 3 O 7 (Nd:BLG), which is very promising for the replacement of Nd:glass for ultrafast sources in multiwatt power applications. A Nd:BLG laser oscillator passively mode-locked and pumped by a Ti:sapphire laser generated pulses of 316-fs duration at 1060 nm, whose spectrum completely fills the fluorescence peak at such wavelength. More interestingly, sub-picosecond pulses were smoothly tunable in a 20-nm range, from 1070 to 1090 nm. The shortest pulses achieved were 290 fs long, centered at 1075 nm.

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