Giancarlo Reali

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.

High-power diode-pumped picosecond Nd 3+ :YVO 4 laser

A diode-pumped Nd(3+):YVO(4) laser passively mode locked by a nonlinear mirror based on second-harmonic generation has been developed. Pumping with a fiber-coupled 10-W diode array, we generated nearly diffraction limited, linearly polarized 11-ps pulses at 1064nm, with average power of 2.7 W at a 150-MHz repetition rate. Pulses as short as 7.9 ps were measured with reduced output power (1.35 W) by optimal focusing in the nonlinear crystal.

Time-resolved M 2 of nanosecond pulses from a Q-switched variable-reflectivity-mirror Nd:YAG laser

Time-resolved M(2) numerical computation and experimental measurements of nanosecond pulses from a Q-switched variable-reflectivity-mirror Nd:YAG laser are presented for the first time to our knowledge. The beam quality parameter is seen to vary approximately from 1 at the beginning to 2 at the end of a high-energy pulse, with a value of 1.35 at the peak of the pulse, which also corresponds to the M(2) obtained from the time-averaged detection of the pulse profile.

Active–passive mode-locked Nd:YAG laser with passive negative feedback

Stationary ultrashort light pulses of 10-psec duration and with an energy of 10 μJ per pulse were obtained from an active-passive mode-locked Nd:YAG laser by using a two-photon absorption limiter (GaAs) inserted into the resonator. The stability of energy in the steady-state part of the pulse train, containing approximately 90 pulses, is better than ±1.5%. The dynamics of the pulse-shortening mechanism are described, and it is shown that maximum pulse compression is reached after only approximately 10 round trips.

Sub-100-fs Cr:YAG laser mode-locked by monolayer graphene saturable absorber

We report on mode-locking of a Cr:YAG laser at 1516 nm using a monolayer graphene-based saturable absorber of transmission type generating 91 fs pulses with a Fourier product of 0.38 at an average output power exceeding 100 mW. Stable single-pulse mode-locked operation without any sign of Q-switching instabilities or multiple pulses is achieved.

430-mW single-transverse mode diode-pumped Nd:YVO/sub 4/ laser at 671 nm

A diode-pumped Nd:YVO/sub 4/ laser operating at 1342 nm and intracavity doubled has been developed. Employing a type II noncritically phase-matched LiB/sub 3/O/sub 5/ (LBO) crystal, we generated 430 mW at 671 nm in single transverse mode. Operating at /spl ap/85% of the maximum output power we also selected a single axial mode.