Stable room-temperature LiF:F2 (+*) tunable color-center laser for the 830-1060-nm spectral range pumped by second-harmonic radiation from a neodymium laser

Simultaneous photostability and thermostability of a room-temperature LiF:F2(+*) tunable color-center laser, with an operating range over 830-1060 nm, pumped by second-harmonic radiation of a YAG:Nd(3+) laser with a 532-nm wavelength has been achieved. The main lasing characteristics of the obtained LiF:F2 (+*) laser have been measured. Twenty-five percent real efficiency in a nonselective resonator cavity and 15% real efficiency in a selective resonator cavity have been obtained. The stable LiF:F2 (+*) laser operates at a 1-100-Hz pulse-repetition rate with a 15-ns pulse duration, a 1-1.5-cm(-1) narrow-band oscillation bandwidth, and divergency of better than 6 × 10(-4). Doubling the fundamental frequencies of F2(+*) oscillation made it possible to obtain stable blue-green tunable radiation over the 415-530-nm range.     

Efficient 550-600-nm tunable laser based on noncritically phase-matched frequency doubling of room-temperature LiF:F2- in lithium triborate

We report on efficient conversion of a 1064-nm Nd:YAG laser to tunable visible light. The conversion scheme uses noncritically phase-matched second-harmonic generation of a pulsed Nd:YAG-pumped LiF:F2- laser in lithium triborate. Optimization yields 42% LiF:F2- laser efficiency and 56% frequency-doubling efficiency, providing >20% conversion from 1064 nm to broadly tunable visible output. A dramatic sensitivity of laser efficiency to pump pulse duration is recorded, with a fundamental efficiency improvement of over 30-fold measured for an increase in pump pulse duration from 5 to 34 ns.     

Diode-Pumped Tunable Room-Temperature LiF:F(2)(-) Color-Center Laser

Pulsed room-temperature tunable operation of a diode-pumped LiF:F(2)(-) laser has been demonstrated for the first time to the author's knowledge. The LiF:F(2)(-) oscillator was tunable in the 1122-1201-nm range. In the free-running mode, with a nonselective resonator, the LiF:F(2)(-) laser showed a 4% optical-to-optical conversion efficiency and a measured 2.5% pumping-to-lasing efficiency at the maximum of the tuning curve for tunable narrow-band operation.     

Comparative study of tunable room-temperature laser operation in the 900-1100-nm range: LiF:F2+ and Ti3+:sapphire

We report on a comparative evaluation of efficient room-temperature solid-state lasers based on Ti:sapphire and LiF:F(2)(+) operating in the 900-1100-nm range. LiF:F(2)(+) lasers are shown to operate with substantially lower threshold, broader tuning, and higher output pulse energies. The shorter fluorescence lifetime in LiF:F(2)(+) leads to higher peak output powers and a considerable reduction in buildup-time fluctuations. The main limitations on LiF:F(2)(+) laser operation are identified as amplified spontaneous emission (ASE) and long-term thermal degradation of the color centers. ASE restricts the tuning range, slope efficiency, and bandwidth of the LiF:F(2)(+) laser for high pump intensity, but broader tuning is achieved with longer pump pulses. The beam quality of the LiF:F(2)(+) laser is comparable with that of the Ti:sapphire laser.     

Diode-pumped LiF:F2+* color center lasertunable in 880-995-nm region at room temperature

Pulsed operation of a tunable LiF:F₂^+* color center laser has been obtained at room temperature under pumping by 680-nm fiber-coupled linear array laser diodes for the first time to the authors knowledge. The LiF:F₂^+* tunable laser operates in 880-995-nm region by use of an intracavity birefringent plate. Using a nonselective resonator the laser showed 3% pumping-to-lasing conversion efficiency. In the tunable narrow band operation the measured optical-to-optical conversion efficiency was 2%. The obtained result is expected to cause more widespread applications of diode-pumped LiF:F₂^+* laser and possibly its commercialization     

Directly Single-Diode-Pumped Continuous-Wave Yb(3+):YAG Laser Tunable in the 1047-1051-nm Wavelength Range

We have demonstrated tunability in a wavelength range of 1047-1051 nm, using the lowest pumping power known to us (1.4 W at 972 nm), for a cw single-diode-pumped Yb:YAG laser. The output power was 166 mW in the multimode regime and 73 mW in the fundamental transverse-mode regime. The laser efficiency was 12.8% and 21% with respect to the incident and the absorbed pump powers, respectively. The linewidth of the laser was Dlambda = 0.05-0.07 cm(-1) (1.5-2.1 GHz), which corresponds to two to three longitudinal cavity modes. A theoretical model of the laser has been developed. Experimental results are in good agreement with the theoretical model.     

Ultrabroadband operation of a cr(4+): forsterite laser by use of a spatially dispersed resonator

Ultrabroadband (half-width of 88 nm) nanosecond Cr(4+):forsterite oscillation was achieved simultaneously in the 1170-1340-nm range (1085 cm(-1)) by use of a spatially dispersed resonator with an intracavity prism pair. The laser demonstrates 4.8% real pump-to-laser efficiency. The oscillation build-up time for different spectral components is around 20 ns and varies by only 2.5 ns in the 1190-1260-nm region, which indicates that the ultrabroadband laser represents a complex multifrequency laser system with nonlinear spectral mode interaction.     

Record-efficient, resonantly-pumped, Er-doped singlemode fibre amplifier

An 85% optical-to-optical efficient, single-frequency performance of resonantly-pumped (at 1476 nm) Yb-free, Er-doped, singlemode fibre amplifier at 1560 nm is reported. The diffraction-limited, single-frequency amplifier is believed to have the highest optical-to-optical efficiency ever reported for Er-doped fibre amplifiers.