Joseph F. Pinto

Additive-pulse mode-locked NaCl:OH − laser

The operation of an additive-pulse mode-locked NaCl:OH(-) color-center laser is described. Stable output pulses as short as 75 fsec have been obtained. The laser is tunable from 1.51 to 1.65microm, with 300 mW of average output power at 1.6 microm.

Stable color-center laser in OH-doped NaCl operating in the 1.41- to 1.81-μm region

A powerful and stable color-center laser based on a perturbed F(2)(+) center has been demonstrated in additively colored NaCl:OH(-) crystals. The OH(-) impurity has been positively identified as the key dopant for creating the color-center laser in NaCl. The laser tunes smoothly over the 1.41- to 1.81-microm region with a maximum cw power of 1.25 W when pumped by a 9-W cw Nd:YAG laser operating at 1.06 microm. Laser operation for periods of several weeks has been monitored with no observable fading in output power. In addition, mode-locked pulses of 5-psec duration have been generated in a synchronously pumped arrangement, tunable from 1.47 to 1.73 microm with an average power of 450 mW at the peak of the tuning curve.

Stable color-center laser in K-doped NaCl tunable from 1.42 to 1.76 μm

Stable, broadly tunable cw lasing has been obtained from color centers in additively colored NaCl doped with K. The laser tunes from 1.42 to 1.76 microm with a peak output power of 530 mW when pumped by 6 W from a 1.06-microm Nd:YAG laser. Output power is strongly enhanced by exposing the crystal to an auxiliary UV light during lasing. No fading of output power has been observed over extended periods. The laser operates at 77 K; however, the crystals can be stored at room temperature. The active color center is tentatively identified as an (F(2)(+))(A) center.

Acousto-optic mode-locked soliton laser

An acousto-optic modulator has been used to actively mode lock a KCl:Tl degrees (1) color-center laser at 1.5 microm. The color-center laser is capable of generating transform-limited pulses as short as 6 psec with 2-W cw pump power. Based on this actively mode-locked KCl:Tl degrees (1) laser a stable soliton laser has been operated, with performance similar to that of the synchronously pumped soliton laser.

Pulsed, room-temperature operation of a tunable NaCl color-center laser

A room-temperature, pulsed, color-center laser using OH(-)-doped NaCl crystals is reported. Crystals were transversely pumped by a Q-switched Nd:YAG laser at 1.06microm and produced output energies of 8.6 mJ in 20-nsec pulses. The tuning range extended from 1.37 to 1.77 microm. During 40 h of operation (>10(6) pulses), a gradual power fading was observed. Laser action is tentatively ascribed to F(2)(+) centers.

Recent progress in color center lasers

Recent progress in the stabilization of laser-active color centers, the discovery of new color center lasers, and the development of new femtosecond sources in the infrared is discussed. The use of impurities such as oxygen to stabilize the F2+ center is described, followed by a description of the recently discovered N-center laser. Finally, the use of color center lasers to produce femtosecond pulses in the 1.5 μm region is reviewed.

Broad Tunability of Flash-Pumped, Tm-Activated Garnet Lasers

We have evaluated the laser performance of flashpumped Cr;Tm -aluminum and scandium garnets and have demonstrated broad tunability from 1.94 μm to 2.09 μm with TEM00 mode output energies exceeding 1 J.

Continuous Wave 3.4 µm Er:YLF Laser

Continuous-wave laser emission at 3.41 μm from an erbium-doped LiYF4 crystal (Er:YLF) at 77 K is reported. Operation of this 4 - level laser is based on the Er3+ 4F9/2 - 4I9/2 transition. An output power of 12 mW and a slope efficiency of 2% have been achieved.

Nonspiking Operation of Flash-Pumped 2-µm Lasers

The output of most pulsed solid state lasers operating in a normal mode Gong-pulse) condition typically exhibits a transient spiking behavior, characteristic of relaxation oscillations. Suppression of this spiking behavior can be achieved by active or passive techniques which introduce an intensity dependent loss inside the laser resonator. In this paper, smooth, long-pulse operation of a flashpumped 2 μm Cr;Tm:YAG laser is achieved utilizing intracavity second harmonic generation.

Tunable, Flashlamp-Pumped Operation of a Cr;Tm:YAG Laser Between 1.945 and 2.014 µm

A tunable, flashlamp pumped, room temperature laser operating in the 1.96 μm wavelength region has been developed in Cr3+ sensitized Tm3+: YAG. Laser action for this system occurs between the lowest Stark level of the 3F4 manifold and various intermediate Stark level splittings of the 3H6 ground state in Tm3+. To date, we have obtained tunable, pulsed operation of the Cr;Tm:YAG laser between 1.945 - 2.014 pm, with maximum output energies of 0.75 J at 1.965 μm.