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1

Intracavity optical parametric oscillator pumped by passively Q-switched Nd:YLF laser

Żendzian W., Jabczyński J. K., Kwiatkowski J.

Opto-Electronics Review

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2009

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Vol. 17, No. 1

45-52

EN

We report on a passively Q-switched end pumped Nd:YLF laser including a noncritically phase-matched KTP singly resonant intracavity optical parametric oscillator (IOPO-KTP). For the Q-switching operation we have used Cr:YAG saturable absorber. The optimized passively Q-switched Nd:YLF laser without IOPO generated linearly polarized pulses of 11.5 ns and 1.07 mJ at 1047 nm. The conversion efficiency of the optimized Q-switched pulse energy at 1047 nm to 1547 nm of a signal approached about 47%. For optimizing both Nd:YLF laser and IOPO we have numerically solved a theoretical model. We have achieved 1.6-ns duration pulses at 1547 nm with energy of 0.5 mJ and peak power of above 300 kW. The beam quality was excellent (M ² ≈ 1).

2

CW mode locked Nd:YVO₄ laser pumped by 20-W laser diode bar

Jabczyński J. K., Żendzian W., Kwiatkowski J.

Opto-Electronics Review

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2006

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Vol. 14, No. 2

135-139

EN

The efficient cw mode locking (cw-ML) regime was demonstrated in Nd:YVO₄ laser by means of saturable absorber mirror (SAM). The 0.3-at.% Nd³⁺ doped 10-mm-long YVO₄ crystal end pumped by 20-W diode module with a beam shaper was applied as a gain medium located in the close vicinity to the rear flat mirror of the first arm of Z-type resonator of 316 cm total length with two curved mirrors of 100-cm curvature radii. The SAM of 2%-saturable absorptance and saturation fluence of 50 μJ/cm² was mounted at the opposite end of a resonator. The developed “dynamically stable” cavity design mitigates detrimental role of thermal aberration in gain medium, enforcing clean perfect mode locking even for the highest pump densities. The cw-ML pulses with 47.5 MHz repetition rate and pulse durations in the range of 15–20 ps were observed for a wide range of pump powers and output coupler losses. In the best case, for 32% of output coupler transmission, up to 6.2 W of average power with near 35% slope efficiency was achieved. The thresholds for Q-switched ML, cw-ML regimes were 2.67 W and 6.13 W of pump power, respectively. For the maximum pump power of 20 W we obtained 133 nJ of pulse energy with 16-ps pulse duration, resulting in a peak power higher than 8 kW. The threshold energy density at SAM giving the QML regime was estimated to be about 30 μJ/cm2, threshold of cw-ML regime was 220 μJ/cm².

3

Q-switched mode locking in diode pumped lasers

Jabczyński J. K., Żendzian W., Kwiatkowski J.

Opto-Electronics Review

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2005

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Vol. 13, No. 4

317-323

EN

The Q-switched mode locking (QML) regime provides the generation of relatively high peak power picosecond pulses train with energies of a few µJ each in a simple resonator. The critical review of QML methods and results including our investigations is given in the first part of presentation. The application of several types of saturable crystalline absorbers (Cr⁴⁺:YAG, V³⁺:YAG, LiF, GaAs) leads to chaotic, partial QML effect, with less than 100% modulation depth in principle. The fully modulated efficient QML laser was demonstrated in the next part. The acousto-optic cell playing a double role of Q-switch and mode locker was located near a flat output coupler. The two folding mirrors were mounted on the translation stages for matching the resonance frequency of the cavity to the radio frequency of acousto-optic modulator. The QML pulses with envelope durations of 100n150 ns and 100% modulation depth were observed for wide range of pump powers and repetition rates. In the preliminary experiments up to 3 W of output average power, 100 µJ of the envelope energy, having approximately 5n8 mode locked pulses were achieved.

4

Iterbowy laser włóknowy typu double-cad o mocy ciągłej 7,2 W

Świderski J., Zając A., Skórczakowski M., Konieczny P.

Elektronika : konstrukcje, technologie, zastosowania

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2004

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Vol. 45, nr 7

21-23

PL

Zaprezentowano praktyczną realizację układu lasera włóknowego dużej mocy. Ośrodkiem aktywnym było dwupłaszczowe włókno kwarcowe domieszkowane iterbem. Układ generował 7,2 W mocy ciągłej na długości fali 1083 nm. Generowana wiązka charakteryzowała się wysoką jakością - parametr M² = 1,05. Sprawność różniczkowa generacji wynosiła 78%.

EN

A practical realisation of a high power fiber laser is presented. An active silica ytterbium-doped double-clad optical fiber was used as an active medium. The laser generated 7,2 W (cw regime) of output power at the wavelength of 1083 nm. The laser beam was characterized by high quality (M² = 1,05). The slope efficiency of geberation equalled 78%.

5

Lasery włóknowe : wysokoenergetyczne źródła promieniowania koherentnego

Świderski J., Zając A., Jankiewicz Z., Skórczakowski M.

Biuletyn Wojskowej Akademii Technicznej

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2004

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Vol. 53, nr 2-3

39-56

PL

Artykuł prezentuje wybrane zgadnienia konstrukcji laserów włóknowych dużej mocy. Tematyka ta jest niezwykle ciekawa, a przede wszystkim aktualna. Lasery włóknowe w literaturze często nazywane są laserami XXI wieku, a parametry promieniowania przez nie generowanego predysponują te urządzenia do wielu aplikacji przemysłowych. Artykuł koncentruje się na specyficznych konstrukcjach włókien aktywnych, stosowanych w układach laserów wysokiej mocy. Prezentują również rekordowe osiągnięcia układów pracy ciągłej i impulsowej.

EN

The paper presents a high power fiber laser issue. This issue is not only very interesting but also up-to-date. In the literature fiber lasers are called the lasers of the 21st century. Parameters of radiation generated by these generators enable these devices to be used in many industrial applications. This article focuses on specific active optical fiber constructions used in high power laser systems, as well as presents record achievements of cw and pulse laser systems.

6

Investigation on passively Q-switched Nd:YAG slab laser pumped by 2D quasi cw diode laser stack

Żendzian W., Jabczyński J.K., Mierczyk Z.

Opto-Electronics Review

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2001

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Vol. 9, No. 1

75-81

EN

The paper presents results of investigations on generation of Nd:YAG triangle slab laser pumped by 2D diode array. The pump beam shape quality with respect to pump/mode overlap efficiency was investigated both theoretically and experimentally. Two cavity schemes with and without pump forming optics were verified in free running and passively Q-switching modes. Slope efficiency of 45% and output energy of 24 mJ for incident 60 mJ of pump energy were achieved in free running mode. Applying Cr⁴⁺:YAG crystal as passive Q-switch, the output energy of 5 mJ and 0.5 MW peak power were obtained in the optimised resonator.

7

High repetition rate, V³⁺:YAG crystal Q-switched diode pumped Nd lasers

Jabczyński J. K., Mierczyk Z., Żendzian W., Kopczyński K., Frukacz Z.

Opto-Electronics Review

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2001

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Vol. 9, No. 1

57-66

EN

The high repetition rate passively Q-switched neodymium host lasers operating at 1 mm wavelenght pumped by a 10-W fibre-coupled diode laser are presented. As a passive q-switch the V³⁺:YAG crystal was applied. The V³⁺:YAG parameters were determined in spectroscopic and saturable transmission experiments. A numerical model taking into account short recovery time of V³⁺:YAG ~ 5 ns and excited state absorption was used to analyse such a laser. The thermal lensing magnitude and performance were determined in free running experiments for two Nd:YAG rods of different quality and Nd:YLF crystal. The smooth Q-switched pulses with repetition rates of 40-200 kHz were abtained in short linear cavities of a length less than 11cm. The highest average power of 1.4 W with slope efficiency of 20% was demonstrated in Nd:YAG laser. Long pulse durations of hundreds ns and low pulse energy of a few mJ (up to 24 in the best case) were caused by low value of the ratio of the absorption cross section of V³⁺:YAG to emission cross section of Nd:YAG. The much higher pulse energy of 70 µJ with pulse duration of 80 ns was abtained in lower gain Nd:YLF laser in a cavity of 140 mm length with internal lens 50 mm focal length.