LBO Crystal Research Articles

Efficient Quasi-Three-Level Laser Operation of Nd:Gd:LuAG Crystal and Blue Light Generation

The quasi-three-level laser operation of Nd:Gd:LuAG crystal is reported for the first time. The maximum continuous-wave (CW) output power of over more than 3 W was obtained with an optical conversion efficiency of 40.0% and a slope efficiency of 55.5%. With Cr:YAG as the saturable absorber, the passively Q-switched laser was achieved with the maximum average output power, shortest pulse width and pulse energy of 820 mW, 21.3 ns, and 124 μJ, respectively. By using a type-II cut LBO crystal as the intracavity frequency doubler, the maximum output power of 802 mW for CW operation and 331 mW for passively Q-switched operation were achieved at the wavelength of 474 nm.

Optical, spectral and phase-matching properties of BIBO, BBO and LBO crystals for optical parametric oscillation in the visible and near-infrared wavelength ranges

The phase-matching properties of BIBO, BBO and LBO crystals for optical parametric oscillators (OPO) with wavelength tuning in the visible and near infrared spectral ranges were numerically investigated. The phase-matching configurations with a pump wavelength of 520 nm that provide the largest effective nonlinearity in each crystal were considered and compared. In addition, dispersive characteristics, including the group velocity mismatch and group velocity dispersion, which are of significant importance in femtosecond OPOs, were calculated. Finally, the attainable gain bandwidths for each crystal were estimated.

All-solid-state doubly resonant intracavity frequency sum mixing orange yellow laser with 3.2 W output power at 593.5 nm

A compact and efficient 593.5 nm orange-yellow laser is realized using doubly resonant intracavity sum frequency mixing. Two Nd: YVO4 crystals are employed as the gain crystals. In two sub-cavities, 1064 nm radiation from one Nd: YVO4 and 1342 nm radiation from the other Nd: YVO4 are mixed to generate 593.5 nm orange-yellow laser. In the overlapping of the two cavities, sum frequency mixing is achieved in a type I critical phase matching (CPM) LBO crystal. An output power of 3.2 W at the wavelength of 593.5 nm is obtained with total incident pump power of 38 W. The optical to optical conversion efficiency is up to 8.4% and the stability of the output power is better than 2.48% in 8 h. To the best knowledge, this it the highest watt-level laser at 593.5 nm generated by diode end pump all-solid-state technology.

High-power 355 nm ultraviolet lasers operating at ultrahigh repetition rate

In this letter, we demonstrate a novel 355 nm ultraviolet (UV) laser operating at ultrahigh repetition rate from 300 kHz to 1 MHz. The hybrid fiber-MOPA–bulk amplifiers based IR source exhibits a high average power of 105 W with near-diffraction-limited beam quality, narrow linewidth and high polarization extinction ratio. Two-cascaded LBO crystals are employed for high efficiency frequency tripling, and a maximum 43.7 W of average UV power is achieved at 400 kHz, corresponding to a conversion efficiency as high as 41.6%. The pulse duration of the UV pulse can be tuned from 5 to 10 ns with good pulse peak stability (better than 2.2% (RMS)).

All-solid-state continuous-wave frequency doubling Nd:LuVO4/LBO laser with 9.6 W output power at 672 nm

An efficient and compact red laser at 672 nm is generated by intracavity frequency doubling of a continuous wave (CW) laser operation of a diode pumped Nd:LuVO4 laser at 1344 nm under the condition of suppression the higher gain transition near 1064 nm. With 38 W diode pump power and a frequency doubling crystal LBO, as high as 9.6 W of CW output power at 672 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 25.3% and the output power stability in 8 h is better than 2.38%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 672 nm generated by intracavity frequency doubling of a diode pumped Nd:LuVO4 laser at 1344 nm.

Phase-matching loci and angular acceptance of non-collinear optical parametric amplification

A general study of phase-matching loci and associated angular acceptances is performed in the case of non-collinear parametric amplification. Numerical and analytical calculations, as well as measurements, are described for the uniaxial BBO crystal and the biaxial LBO crystal.

All-solid-state continuous-wave frequency doubling Nd:YAG/LBO laser with 8.2 W output power at 660 nm

An efficient and compact red laser at 660 nm is generated by intracavity frequency doubling of continuous wave (CW) laser operation of a diode pumped Nd:YAG laser at 1319 nm under the condition of suppression the higher gain transition near 1064 and 1319 nm under the condition of suppression the higher gain transition near 1064 and 1338 nm. With 40 W diode pump power and a frequency doubling crystal LBO, as high as 8.6 W of CW output power at 660 nm is achieved, corresponding to an optical-to-optical conversion efficiency of 21.5% and the output power stability in 8 h is better than 2.73%. To the best of our knowledge, this it the highest conversion efficiency of watt-level laser at 660 nm generated by intracavity frequency doubling of a diode end pumped Nd:YAG laser at 1319 nm.

Cascaded frequency doublers for broadband laser radiation

A new scheme of a cascaded converter of the first harmonic of broadband cw laser radiation into the second harmonic (SH) with compensation for the group walk-off in cascades is proposed and investigated. The conditions under which high conversion coefficients of broadband (∼33 cm-1) single-mode fibre laser radiation with low peak power (∼300 W) into the SH are determined for frequency doublers based on the most promising LBO crystal. Conversion of cw radiation with an average power of 300 W and efficiency η = 4.5 % into the SH is obtained in a single LBO crystal. Effect of coherent addition of SH radiation excited in different cascades is demonstrated for two- and three-stage schemes. The expected conversion efficiencies, calculated disregarding loss but taking into account real aberrations of elements, are 18 % and 38 %, respectively. The effect of pumping depletion begins to manifest itself in the third cascade of a three-stage converter; it may reduce the latter value to ∼30 %.

A sensitive observation of the photo-refraction effects in BIBO and LBO crystals basing on the loss modulation of laser intracavity

We present a sensitive scheme basing on the sensitive intracavity loss modulation to observe photo-refraction (PR) effects of some nonlinear crystals usually used for optical parametric chirped pulse amplification (OPCPA), e.g. BIBO and LBO, pumped by the second harmonic (SH) of intense 800nm ultrashort laser pulse chain. Our results show that the dynamical PR effects of BIBO and LBO crystals need about 10s to reach a steady state or to fade away after their pumping switch on or off. These data imply that using these kinds of crystals for multi-stages OPCPA with the repetition rate from some Hz to tens of Hz, it may be necessary to consider the deterioration of the OPCPA stability due to the PR effects. However, if the repetition rate is high (∼kHz) or low enough (<0.1Hz), the PR effects become negligible for the stability.

Passively Q-switched mode locking in a compact Nd:GdVO4/Cr:YAG self-Raman laser

Passively Q-switched mode locking in a compact Nd:GdVO4 self-Raman laser with a Cr:YAG saturable absorber was demonstrated. The picosecond first stokes at 1173nm was successfully obtained. When the optical cavity length changed from 167mm to 120mm, the mode-locked pulse repetition rate increased from 0.9GHz to 1.25GHz. At the maximum diode pump power of 10W and with a pulse repetition rate of 0.9GHz, an average output power up to 105mW has been achieved at 1173nm. In addition, the yellow laser output at 586.5nm was also realized by frequency doubling with an LBO crystal.

Nd:GdVO4 self-Raman laser using double-end polarised pumping at 880 nm for high power infrared and visible output

We report and evaluate a novel double-end polarised 880 nm pumping scheme for a Nd:GdVO4 self-Raman laser, aimed at efficiently generating high output powers in the near-infrared and visible. Compared to conventional single-end pumping, this pump scheme has significant benefits in terms of absorption efficiency, temperature effects in the crystal, and mode-matching between the pumping beam and TEM00 resonator mode. The maximum first-Stokes output powers were 4.1 W for CW operation and 5.63 W for quasi-CW (50 % duty-cycle) operation, with the diode-Stokes conversion efficiency of 11.2 % and 10.3 %, respectively. Visible emission was also realised by intra-cavity frequency-doubling (586.5 nm) or sum-frequency-generation (559 nm) using BBO or LBO crystals. For CW operation, the maximum output power was 3.46 W at 586.5 nm and 4.05 W at 559 nm, with diode-visible conversion efficiency of 10.7 % and 12.5 %; while for quasi-CW operation (50 % duty-cycle), the maximum output peak power was 6.5 W at 586.5 nm and 9.2 W at 559 nm, corresponding to 13.1 % and 18.9 % diode-visible conversion efficiency.

Multiwavelength green-yellow laser based on a Nd:YAG laser with nonlinear frequency conversion in a LBO crystal

We demonstrate a multiwavelength laser in the green-yellow region by means of a diode-pumped neodymium-doped yttrium aluminum garnet laser. This laser system combines a homemade 1074 nm and 1112 nm dual-wavelength laser with extracavity second harmonic generation (SHG) or sum-frequency generation in a lithium triborate crystal to generate visible output at any one of three wavelengths, 537 nm, 546 nm, and 556 nm, by simple temperature tuning, which has an important application in detecting carbon monoxide. The maximum average output power at the three wavelengths (537 nm, 546 nm, and 556 nm) was obtained to be 10.5 W, 0.5 W, and 8.5 W, respectively. The maximum SHG conversion efficiency from the infrared to the visible spectral region was about 51%.

All-solid-state CW Nd:GdVO4-LBO red laser under direct 912 nm pumping

We report a red laser at 670.5 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1341 nm Nd:GdVO4 laser under in-band diode pumping at 912 nm. An LBO crystal, cut for critical type I phase matching is used for second harmonic generation of the laser. At an incident pump power of 8.9 W, as high as 347 mW of CW output power at 670.5 nm is achieved. The fluctuation of the red output power was better than 3.7% in the given 30 min, and the beam quality factor M 2 is 1.65.

Continuous-wave VECSEL Raman laser with tunable lime-yellow-orange output

We report a compact CW KGW Raman laser with intracavity nonlinear mixing, pumped by the intracavity field of a VECSEL. By temperature tuning an intracavity LBO crystal, we obtained two separate tunable emissions bands, namely 548.5 - 566 nm for sum-frequency-generation (SFG) of the fundamental and Stokes wavelengths, and 577.5 - 596 nm for second-harmonic-generation (SHG) of the Stokes wavelength. The maximum output powers for SFG and SHG were 0.8 W @ 560 nm and 0.52 W @ 592.5 nm, with corresponding diode-to-visible optical conversion efficiencies of 4.2% and 2.9%. These preliminary results show strong potential for expanding the spectral coverage of VECSEL lasers.

555 nm laser sources based on intracavity frequency doubling of Nd:YGG laser

We report for the first time a yellow-green laser at 555 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1110 nm Nd-doped yttrium gallium garnet (Nd:YGG) laser under in-band diode pumping at 808 nm. An LBO crystal, cut for critical type I phase matching is used for second harmonic generation of the laser. At an incident pump power of 18.5 W, as high as 2.31 W of CW output power at 555 nm is achieved. The optical-to-optical conversion efficiency is up to 12.4%, and the fluctuation of the yellow-green output power was better than 2.8% in the given 4 h.

Diode pumped Nd:Lu0.5Y0.5VO4-LBO red laser at 671 nm

We report a efficient compact red laser at 671 nm generation by intracavity frequency doubling of a continuous wave laser operation of a diode pumped Nd:Lu0.5Y0.5VO4 laser on the 4 F 3/2-4 I 13/2 transition at 1342 nm. An LBO crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At an absorbed pump power of 17.8 W, as high as 2.25 W of continuous wave output power at 671 nm is achieved with 10-mm-long LBO. The optical-to-optical conversion efficiency is up to 12.6%, and the fluctuation of the red output power was better than 3.6% in the given 30 min.

OPTICAL COATINGS FORMED BY GRADIENT REFRACTIVE INDEX MATERIALS / METALŲ OKSIDŲ IR JŲ MIŠINIŲ PANAUDOJIMAS KINTAMO LŪŽIO RODIKLIO OPTINĖMS DANGOMS FORMUOTI

Recent advances in ion beam sputtering technology enabled efficient deposition of different oxide mixture coatings. In the present investigation, coating materials ZrO2and SiO2 were utilized for the synthesis of different mixtures. The goal of the conducted investigation was to explore the potential of ZrO2/SiO2 mixtures, especially for applications in the range of the UV spectral. Deposited dielectric mirrors having classical quarter-wave and “rised” design with ZrO2/SiO2 mixture for 266 nm and 355 nm showed good resistance to laser radiation. We also investigated the “fatigue” behavior of LIDT’s in LBO crystals with single, dual and triple wavelength anti-reflective coatings (AR@355, AR@532+1064 and AR@355+532+1064) in order to optimize design and layer materials. The influence of gradient refractive index profiles on damage resistance is of a special interest. We selected a few designs of antireflective coatings which demonstrated the best resistance to laser radiation. An experimental study on rugate filter coatings showed the need for a more accurate characterization of optical properties of metal oxides and their corresponding mixtures. Santrauka Šiame darbe tiriamas jonapluoščio dulkinimo technologija dengtų ZrO2/SiO2 ir jų mišinių optinių savybių pritaikymas kintamo lūžio rodiklio (Rugate tipo) optinėms interferencinėms dangoms formuoti. Mišiniuose naudojant mažą ZrO2 frakciją, buvo išplėstas šios medžiagos pritaikymas UV srityje. Remiantis gautais rezultatais, suformuotos didelio atspindžio (HR) ir skaidrinančios (AR) dangos esant λ = 355 nm bangos ilgio spinduliuotei, taip pat teoriškai sumodeliuotos ir suformuotos daugiabangio skaidrinimo (AR@ 355+532+ 064) Rugate tipo dangos ant LBO (LiB3O5) netiesinių kristalų. Palygintos šių dangų optinės savybės su tomis dangomis, kuriose panaudoti gryni metalo oksidai (fiksuoto lūžio rodiklio). Atliktas Rugate tipo dangų, pasižyminčių siaura didelio (R &gt; 99,9 %) atspindžio zona ties 532 nm ir pralaidumu likusioje spektro dalyje, teorinis modeliavimas ir eksperimentinis garinimas.

LBO晶体长度对全固态473 nm蓝光激光器效率的影响

LBO晶体长度对全固态473 nm蓝光激光器效率的影响

Diode-pumped continuous-wave Nd3+:YAlO3 intracavity-doubled red laser

It is reported that efficient continuous-wave (CW) red laser generation at 670 nm in a LBO crystal at type-I phase matching direction performed with a diode-pumped Nd3+:YAlO3 (Nd:YAP) laser. With incident pump power of 15.6 W, output power of 273 mW at 670 nm has been obtained using a 10 mm-long LBO crystal. At the output power level of 273 mW, the output stability is better than 3.7%.

All solid-state CW Nd:LuVO4-LBO yellow-green laser under direct 888 nm pumping

We report a yellow-green laser at 544.5 nm generation by intracavity frequency doubling of a continuous wave (CW) laser operation of a 1089 nm Nd:LuVO4 laser under in-band diode pumping at 888 nm. An LBO crystal, cut for critical type I phase matching is used for second harmonic generation of the laser. At an incident pump power of 17.9 W, as high as 3.81 W of CW output power at 544.5 nm is achieved. The optical-to-optical conversion efficiency is up to 21.3%, and the fluctuation of the yellow-green output power was better than 3.7% in the given 4 h.