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A low threshold Cr:LiSAF laser pumped with an inexpensive single-mode laser diode emitting 120 mW was passively mode-locked with a novel ultrafast saturable absorber mirror based on single-walled carbon nanotubes (SWCNT-SAM). Pulses as short as 122 fs were achieved, tunable across 14 nm. A second pump diode coupled in polarization allowed to shorten the pulse duration to 106 fs, with up to 24-mW output power.

We present a compact Nd:silicate laser pumped by a single 1-W high-brightness commercial laser diode that generates pulses as short as 88 fs (nearly Fourier limited) when passively mode-locked with a saturable absorber mirror. We also tested a prismless cavity setup employing a single Gires–Tournois mirror, yielding 100-fs pulses. These setups are significantly simpler and more compact than those reported previously for short pulse Nd:silicate lasers.

We report about a PPKTP optical parametric oscillator synchronously pumped by a picosecond Ti:Sapphire laser. The system is tunable in the spectral region around 1.55 μm which corresponds to the degeneracy wavelength. Nevertheless, it is able to deliver transform-limited pulses thanks to the insertion of a properly designed birefringent filter which ensures single-frequency operation as well. The resonating wavelength can be tuned for more than 100 nm by a simple rotation of the filter and is proven to be insensitive to cavity length detuning and pump wavelength drift.

A diode array pumped nonlinear mirror mode-locked (ML) laser is developed and the regime of the stable operation for such a system is found to occur for a little detuning of intra-cavity second harmonic phase-matching. The existing theory of mode-locking using a fast saturable absorber (FSA) is used to derive corresponding equivalent parameters for a fast nonlinear mirror saturable absorber. The condition for stable single pulse ML operation is evaluated in terms of small signal gain of the laser medium and small signal nonlinear loss. The analysis explains the experimental observations and differentiates the regime of operation in ML, Q-switching and cw mode-locking.

A technique based on the analysis of the output power as a function of the output coupler reflectivity is investigated for the determination of pump-induced losses in end-pumped solid-state lasers. The thermal diffractive losses measured for a standard Z-folded resonator are in fair agreement with theoretical predictions. Wavefront distortions as small as λ/63 (rms) have been measured.

Single-mode diodes enable a particularly simple, compact and effective pumping of solid-state laser devices for many specialized applications. We investigated a single-mode, 300-mW laser diode for pumping at 935 nm a Yb:YAG laser passively mode-locked by a semiconductor saturable absorber. Relatively short pulse generation (156 fs), tunable across 1033–1059 nm has been demonstrated. An optical-to-optical efficiency of about 28% has been obtained with 320 fs long pulses. Therefore, contrarily to what previously believed, compact diode-pumped ultrafast Yb:YAG oscillators can reliably and efficiently deliver pulses in the range of ≈ 100–200 fs with few tens of mW, which are very appealing for bio-diagnostics and amplifier seeding applications.

A diode-pumped Nd:YVO 4 laser passively Q-switched and mode locked by V 3+ :YAG generates as much as 505-mW average power at 1342 nm (30% of the cw output) in trains of sub-nanosecond pulses with energy as high as 0.7 μJ and repetition rates in the range 10–50 kHz.

We report the characterization of a synchronously-pumped Kerr-lens mode-locked (KLM) femtosecond Cr 4+ :forsterite laser, generating 66 fs pulses at 1240 nm, with ≈ 200 mW output power. The influence of the induced thermal lensing on the fast Kerr modulation is analysed by a simple model, which shows that the conventional criteria employed for KLM optimization of Ti:sapphire must be revised when considering the strong thermal effects induced in the Cr 4+ :forsterite crystal. Indications from our simple model agree with the experimental results.

A medium-power all-solid-state diode-pumped cw Nd:YAG laser, passively Q -switched employing Cr 4+ :YAG as saturable absorber, has been developed. Optimum coupling operation at the 1064 nm working wavelength resulted in 100 μJ, 36 ns, nearly diffraction limited pulses at 15 kHz repetition frequency, with 1.5 W average power output. We discuss the characterisation of the passive Q -switching elements and the laser operation.

We developed an all-solid-state Cr4+:forsterite laser pumped by a kHz Q-switched diode-pumped Nd:YAG oscillator. The laser is tunable from 1190 to 1310 nm, and generates pulses with duration ≈ 70–100 ns and maximum energy ≈ 14 μJ at 1230 nm, corresponding to a pumping efficiency ≈ 10%. This system could be employed as a regenerative amplifier in an ultrafast all-solid-state system based on Cr4+:forsterite.

The starting of Kerr lens mode-locking operation can be successfully understood by a simple ABCD resonator analysis, which discards the diffractive effects introduced by the hard aperture of the laser cavity. These effects are nevertheless important since they change the intracavity beam shape and need to be considered to explain the observed unidirectional operation in ring resonator configurations. We present a model analysis which, using a Gaussian apodizing aperture, rigorously includes the diffraction of the circulating cavity eigenmode by the aperture.

We report on degenerate four-wave mixing results of differently doped GaAs samples, obtained with 30 ps pulses at λ=1.064 μm. From the value of the effective third order nonlinear susceptibility measured at low fluences we derive the refracting index change per carrier. At higher fluences, two-photon absorption becomes dominant, and the behavior of the reflectivity is accounted for by a numerical model.

We present an experimental study of phase-conjugation Nd:YAG laser oscillators, using a stimulated Brillouin scattering mirror. Depending upon the cavity configuration, Q -switching is provided either by a nonlinear acetate sheet before the stimulated Brillouin scattering takes place or self-starts within the Brillouin cell with no need for any further shutter. In both cases, employing proper mode selectors, pulses of near diffraction-limited divergence, energies from 10 to over 150 mJ, and durations of 10 to 20 ns were generated. A simple model of the self- Q -switching dynamics is also presented.

We demonstrate that the pulses from a passively mode-locked flashlamp pumped solid-state laser can be considerably shorter using an antiresonant-ring mirror than using a linear cavity with a standard contacted dye-cell mirror, and we suggest that transverse-mode-filtering effects in the antiresonant ring play an important role in explaining this difference.

The theory of pulse shortening and train stretching in passively mode-locked solid-state laser, controlled by a passive negative feedback, is presented for the case of an intra-cavity two-photon absorbing semiconductor feedback element. It is shown that it acts simultaneously as power limiter and pulse compressor, ensuring optimum operation of the intra-cavity saturable absorber, and generating very long and stable trains of energetic, almost bandwidth limited pulses.