CW Laser Output Research Articles

High-power quasi-cw laser pulses via high-gain diode-pumped bulk amplifiers

By pulse-slicing from a cw laser output and then providing high gain amplification, one can obtain quasi-cw pulses at powers well in excess of those available from cw lasers. The use of this demonstrated with a cw, additive-pulse-mode-locked Nd:YLF laser. Mode-locked pulse trains with an envelope of ∼ 10 μs duration and repetition rate of 2 kHz are amplified in a × 20 gain, double-pass Nd:YLF bulk amplifier pumped by a 4 W diode. Amplified power levels allow efficient single-pass frequency doubling in LBO followed by efficient synchronous pumping of an LBO optical parametric oscillator.

Diode pumped CW Nd:YAG laser operating at 938.5nm

Efficient operation of a Nd:YAG laser on the quasi-three-level transition at 938.5 nm, end-pumped by a 20 W diode bar is reported. For the maximum available incident power of 13.6 W we have obtained a CW laser output at room temperature of 2.0 W in a near diffraction-limited TEM00 beam.

LD pumped Nd:YAG laser.

Three types of LD pumped Nd: YAG laser are described. (1) In a “Lens focused LD end pumped Nd: YAG laser”, a cw laser output power of 290mW is obtained at an LD output power of 1.3W. (2) In an “LD directly coupled micro Nd YAG slab laser”, an LD beam is reflected at the upper and lower surfaces of a micro-slab, thereby bringing about excitation area small enough to give a TEM00 Nd: YAG laser beam. (3) In an “off-centered LD side pumped Nd: YAG laser”, a cw 1-W Nd: YAG laser beam of a stable output power is obtained at a pumping power of 8.4W.

Diode pumped NYAB green laser.

A new diode-pumped green laser has been demonstrated. A NYAB (Ndχ y1-χ Al3 (B03) 4), self-fre quency-doubling Laser crystal of type I, was pumped by a broad area laser diode. The threshold pumping power is 4.7 mW. We obtained cw green laser output up to 16 mW (0.531 μm) with a conversion efficiency of 4.4%.

1.3 µm high-power BH laser on p-InP substrates

In our fabrication of a 1.3 μm band high-power BH laser on a p-type InP substrate, 79 mW CW laser output was obtained, and the spectrum width was 10 nm at 50 mW; it also obtained a high-power pulse output of more than 200 mW at 30 ns pulse width. It shows high-speed pulse response at 2 Gbits/s. These CW and pulse lasing characteristics are reported in this paper, and we also show the output and threshold current distribution of about 1000 samples from six wafers. This high-power laser is very useful for light sources of measuring instruments.

KZnF 3:Cr 3+ — A tunable solid state NIR-laser

Pulsed laser operation at room temperature and cw laser output below 260 K has been demonstrated with the laser material KZnF 3:Cr 3+ in the spectral range between 775—826 nm. The system can be tuned by dispersive elements in the resonator or by temperature variation.

New method for detecting transient gain (or loss) in pulsed gas discharges

A pulsed argon discharge inside a CW-laser cavity is used to modulate the CW-laser output via the transient gain/loss at various lasing wavelengths. Under short-pulse excitation ( <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">\sim 0.6 \mu</tex> s), gain is found at four Ar(II) lasing lines, but losses are observed at 4880 and 5017 Å. A similar diagnostic device with broad-band capabilities and based on an ion-laser-pumped dye laser is proposed.

Electronic- and phonon-terminated laser emission from Ho&amp;lt;sup&amp;gt;3+&amp;lt;/sup&amp;gt;in BaY&amp;lt;inf&amp;gt;2&amp;lt;/inf&amp;gt;F&amp;lt;inf&amp;gt;8&amp;lt;/inf&amp;gt;

Infrared spontaneous and stimulated emission from Ho <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> in BaY <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">2</inf> F <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</inf> is reported. In addition to the familiar <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_{7} \rightarrow</tex> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">8</inf> transition at 2 μ, <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F_{5} \rightarrow</tex> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> emission at 2.4μ and <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">I_{6} \rightarrow</tex> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">7</inf> emission at 2.9μ are discussed. There are several unusual features of the 2-μ laser emission. At room temperature, phonon-terminated laser emission is observed at 2.171 μ. At 77 K a complex CW laser output is observed in a wavelength interval lying on the shoulder of a fluorescence line. The complex output is attributed to oscillation in transverse modes of the resonator. Oscillation is not observed in the strongest emission line, despite a large terminal state splitting of 310 cm <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">-1</sup> . These results are explained on the basis of a theory developed earlier for transition metal ion lasers. The validity of the model is supported by demonstrating the tunability through loss modulation predicted by theory. The observation of these effects is made possible by the very low internal scattering loss in the crystals. The <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> <tex xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">F_{5} \rightarrow</tex> <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</sup> I <inf xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">5</inf> laser lines near 2.4 μ represent relatively low gain transitions with pulse durations limited by accumulation in a longer lived terminal state. The dynamics of laser emission indicate the possible absence of thermal equilibrium in the excited state. For the 2.9-μ transition the bottleneck posed by a longer lived terminal state may be eliminated by the addition of Eu <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> or Pr <sup xmlns:mml="http://www.w3.org/1998/Math/MathML" xmlns:xlink="http://www.w3.org/1999/xlink">3+</sup> , but laser emission could not be obtained.