Annalisa Guandalini

Generation of intense few-cycle laser pulses through filamentation – parameter dependence

Intense few-cycle laser pulses as short as 5.1 fs are generated though self-filamentation in a noble gas atmosphere. We study the dependence of the laser pulse fidelity on the driving pulse profile and chirp as well as on the gas parameters, quantify their pointing stability and spatial quality.

Diode pumped Nd:YVO4 laser at 1.34 μm Q-switched and mode locked by a V3+:YAG saturable absorber

Abstract 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.

Efficient 671-nm pump source by intracavity doubling of a diode-pumped Nd:YVO 4 laser

A diode-pumped, intracavity-doubled Nd:YVO4 laser, generating as much as 760 mW of power at 671 nm, which was used to efficiently pump a Cr:LiSAF laser, is described. A slope efficiency of ≈39% with maximum continuous-wave output power of >180 mW was achieved with this system. Experiments in tunability and generation of ultrashort pulses are also reported.

Optical spectroscopy and diode-pumped laser performance of Nd/sup 3+/ in the CNGG crystal

We have exploited the broad absorption and emission bandwidth of the laser crystal Ca/sub 3/(NbGa)/sub 2-x/Ga/sub 3/O/sub 12/ doped with Nd/sup 3+/ to develop a tunable and mode locked diode-pumped 1.06 /spl mu/m laser. We also present the fluorescence and excitation spectra at different crystal temperatures from 10 to 298 K. The spontaneous transition probabilities, the branching ratios, and the radiative lifetime are calculated by means of the Judd-Ofelt theory and compared with the experimental results. The stimulated emission cross-sections of the most important transitions have been calculated and compared with laser results. Employing a 2-W laser diode as a continuous-wave pump source, we have been able to tune the emission wavelength in the range 1053-1074 nm. Active mode-locking yielding pulses of 9.6, 18, and 19.7 ps at the three main emission peaks of 1058.6, 1061.2, and 1065.3 nm, respectively. was also demonstrated.

40-fs Yb 3+ :CaGdAlO 4 laser pumped by a single-mode 350-mW laser diode

We report the results of the investigation on a passively mode-locked Yb(3+):CaGdAlO(4) laser, pumped by a single transverse mode laser diode emitting 350 mW at 980 nm. This particular pump source allows efficient pumping with a nearly TEM(00) beam and minimal thermal load, making the optimization of the mode-locking performance more straightforward than with higher-power multimode beams. Indeed, using a semiconductor saturable absorber mirror and extra-cavity dispersion compensation, pulses as short as 40 fs (31-nm spectrum) have been measured, tunable across 20 nm with 15-mW output power. Slightly longer Fourier-limited 46-fs pulses with 33 mW output power directly from the oscillator have been achieved, using a different saturable absorber mirror. Such overall performance, especially considering these are among the shortest pulses generated in diode-pumped ytterbium lasers, confirms the excellent qualities of Yb(3+):CaGdAlO(4).

High-brightness 2.4-W continuous-wave Nd:GdVO4 laser at 670 nm.

We report on a diode-pumped 1.3-microm Nd:GdVO4 cw laser, intracavity doubled for highly efficient generation of red light. We obtained as much as 2.4 W of power at 670 nm (corresponding to 26% optical-to-optical efficiency) in a nearly TEM00 mode and with small amplitude noise. To the best of our knowledge, these results represent the highest performance at this wavelength for cw solid-state lasers.

5.1 fs pulses generated by filamentation and carrier envelope phase stability analysis

Intense 5.1 fs CEO (carrier envelope offset) phase stable pulses were generated through two-fold filamentation in a noble gas at atmospheric pressure. The preservation of the CEO phase during the filamentation process was investigated. We show that generating these short pulses using filaments is not detrimental for the CEO phase stabilization, and that the more than one octave-spanning spectrum intrinsically generated by the process is feasible, and offers certain benefits, for direct use in single shot f–2f spectral interferometry.

28-W, 217 fs solid-state Yb:CAlGdO4 regenerative amplifiers.

A new high-performance Yb:CaAlGdO(4) (Yb:CALGO) regenerative amplifier is demonstrated. Pumped by 116 W at ≈980 nm and seeded by means of a 92 fs oscillator, it generates as much as 36 W of average output power with chirped pulses, and 28 W with 217 fs compressed pulses at 500 kHz repetition rate. This corresponds to 56 μJ of pulse energy and 258 MW peak power. The compressed pulses have a time-bandwidth product of 0.69 and could be shortened further with an improved compressor setup.

Application of V3+:YAG crystals for Q-switching and mode-locking of 1.3-μm diode-pumped neodymium lasers

High-power passive Q-switching and mode-locking operation regimes of diode end-pumped Nd:YAG, Nd:YVO4, and Nd:YAP active media, operating at a 1.34-?m wavelength are investigated with V3+:YAG crystal as the saturable absorber. The highest average power of 2.1 W results from a Nd:YVO4 crystal placed in a 70-mm-long linear cavity. The corresponding pulse peak power and width are 0.1 kW and 133 ns, respectively. Employing a Nd:YAP crystal and 35-mm cavity length, the highest peak power of ~2.8 kW results when the laser runs at a 6.5-kHz repetition rate for an average power of —0.4 W. A record of 79-xJ pulse energy results from a 64-mm-long resonator with Nd:YAG gain media, however, for a decreased average power of ~0.24 W and pulses of 40-ns width. The mode-locking operation regime is investigated in a Z-type cavity. The best results, namely, ~0.5 W average power with mode-locked envelope energy in excess of 30 ?J and mode- locked pulse energy of 0.7 ?J, are obtained from the Nd:YVO4 media. Trains of 1-?s-wide pulses with improved stability result from a 1.5-m- long designed cavity with KTP crystal applied for passive negative feedback. A numerical modeling that takes into account the short recovery time of V3+:YAG saturable absorber (~5 ns) and excited state absorption effect is used to analyze and obtain general rules for optimizing such lasers.

Diode-pumped passively mode-locked and passively stabilized Nd3+:BaY2F8 laser.

Continuous-wave mode locking (CW-ML) of a diode-pumped Nd3+:BaY2F8 laser is reported for the first time to our knowledge. Pulses as short as 4.8 ps were measured with a total output power of approximately 1 W at 1049 nm, corresponding to 3.4 W of absorbed power from the pump diode at 806 nm. A novel technique for passive stabilization of CW-ML has been demonstrated.