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Diode-pumped Nd:YCOB self-frequency-doubling blue laser at 468 nm
Abstract
We report a continuous-wave (CW) self-frequency-doubling blue laser at 468 nm by a diodepumped Nd3+:YCa4O(BO3)3 (Nd:YCOB) laser. With 14.3 W of diode pump power, a maximum output power of 211 mW in the blue spectral range at 468 nm has
been achieved. The beam quality M2 values were equal to 1.16 and 1.23 in X and Y directions, respectively. The output power stability over 30 min is better than 5%. To the best of our knowledge, this is
the highest power laser at 468 nm generated by self-frequency doubling of a diode pumped Nd:YCOB laser.
We demonstrated the output power scaling of a self-frequency-doubled (SFD) laser with ${\rm Nd}:{{\rm GdCa}_4}{\rm O}{({{\rm BO}_3})_3}$Nd:GdCa4O(BO3)3 (Nd:GdCOB) crystal by employing a partially end-pumped slab structure and optimized laser-diode (LD) pump wavelength. Associated with the theoretical calculation about the thermal distribution in the SFD Nd:GdCOB crystal, the maximum SFD output power was achieved to be 17.91 W at the wavelength of 545.5 nm, which represents the highest output power in SFD lasers, and the optical conversion efficiency from the LD to SFD laser power reached up to 20%. Since the wavelength at 545.5 nm is located at the eye-sensitive spectral region and the SFD lasers have the advantages in the compact structure, the demonstrated SFD laser should have promising applications in some regimes such as laser display, medical, military, and scientific research.
We report a blue laser at 452 nm generation by intracavity frequency doubling of a continuous wave (cw) laser operation of a 904 nm Nd:LGS laser under 808 nm diode pumping. A LiB3O5 (LBO) crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation (SHG) of the laser. At an incident pump power of 17.8 W, as high as 1.14 W of cw output power at 452 nm is achieved. The optical-to-optical conversion efficiency is up to 6.4%, and the fluctuation of the blue output power was better than 4.1% in the given 30 min.
We present a theoretical and experimental analysis of a
diode-pumped Yb<sup>3+</sup>-doped
Ca<sub>4</sub>GdO(BO<sub>3</sub>)<sub>3</sub> (Yb:GdCOB) laser. A new
model for a diode-pumped quasi-three-level laser is described. The
effects of absorption saturation, temperature profile, and the beam
quality M<sup>2</sup> factor of the pump diode have been taken into
account, for the first time to our knowledge. We have obtained a good
agreement between experimental measurements and theoretical calculations
with two different pump wavelengths, 902 and 976 nm. Our model has given
good predictions of the laser performances for different crystal
temperatures and different M<sup>2</sup> factors of the pump beam. As
much as 440 mW of output power (at 1082 nm) have been achieved for 640
mW of absorbed pump power at 976 nm, corresponding to one of the highest
slope efficiencies (81%) ever obtained with Yb-doped lasers
The surge of interest in ytterbium-doped materials has led to their being proposed as substitutes for their widely used neodymium counterparts for infrared laser emission. Spectroscopic and laser investigations of ytterbium-doped Ca4GdO(BO3)(3) (Yb:GdCOB), a new ytterbium-doped crystal, are reported. Laser performances under titanium:sapphire pumping suggest that this material is suitable for schemes that include laser-diode pumping. A maximum slope efficiency of 58.8% with a corresponding laser threshold of 40 mW has been demonstrated with a 1% output coupler. Laser oscillations were also observed for output-coupler transmissions of as much as 10%. Self-frequency doubling of infrared-laser emission has been observed for the first time to our knowledge in an ytterbium-doped medium. The recent demonstration of the interesting self-frequency-doubling properties of neodymium-doped Ca4GdO(BO3)(3) suggests that Yb:GdCOB could also be efficient in visible laser emission because of its lack of reabsorption at the second-harmonic wavelength. All these results show that the calcium oxoborate family can be useful compact and efficient laser-diode-pumped visible-laser sources. (C) 1999 Optical Society of America [S0740-3224(99)00201-5] OCIS codes: 160.4330, 160.4670, 160.3380, 140.3580.
Optically pumped, external-cavity, surface emitting semiconductor lasers (also known as optically pumped semiconductor lasers, OPS lasers, and vertical external cavity surface emitting lasers, VECSELs) generate near-diffraction limited beams from low brightness diode-array pumps. We have demonstrated 30 W cw at 980 nm and 15 W cw at 488 nm in a single spatial mode from these emitters and believe they can be scaled to > 100 W. Potential applications we have explored for such devices include wavelength conversion, spectral and spatial brightness conversion.
We report on a simple, compact continuous-wave 456-nm laser by intracavity frequency doubling of an end-pumped Nd:GdVO4 laser on the 4
F
3/2 → 4
I
9/2 transition. A 5-mm-long, 0.2-at % Nd:GdVO4 bulk crystal is employed as the gain medium and the Nd3+ ion is directly pumped into the emitting level (4
F
3/2) by a novel 879-nm laser diode. Intracavity frequency doubling with a 15-mm-long LBO crystal and a 10-mm-long BiBO crystal
in a linear cavity yield 56- and 118-mW single-ended blue outputs at the absorbed pump power of 11.9 W, respectively. The
corresponding values are scaled to 286 and 391 mW, respectively, in a V-type cavity, with optical conversion efficiencies
of 2.4 and 3.3% versus the absorbed pump power. The fluctuations of the 456-nm output power for both cases are less than 3%
at the maximum output level.
Sum-frequency mixing in neodymium-doped YAl <sub> 3 </sub> (BO <sub> 3 </sub> ) <sub> 4 </sub> of its fundamental laser line at 1062 nm and the pump light from a tunable Ti:sapphire laser has been used to generate blue radiation from 435 to 465 nm in an end-pumped configuration. In nonoptimal preliminary experiments 22 μW at 458 nm was obtained out of 200 mW absorbed power at 807 nm. Nd:YAB, therefore, emerges as a promising laser material for diode-pumped solid-state lasers in the blue spectral region. © 1998 American Institute of Physics.
We present three different dual-wavelength laser architectures to obtain cw blue radiations. They are based on diode-pumped Nd-doped crystals lasing on the 4F3/2-4I11/2 and 4F3/2-4I9/2 transitions. Blue radiations were achieved by intracavity sum frequency operation in a BiB3O6 crystal. We report a maximum output blue power of 303 mW at 491 nm for a pump power of 10 W.
In this paper the laser properties of Nd3+ ion in yttrium aluminum borate crystal are systematically investigated under continuous-wave end pumping by using a Ti:sapphire tunable laser. Spectral characteristics in the diode-pumping region are analyzed, and no significant excited-state absorption of pumping radiation is predicted. Internal losses are determined to be as low as 0.02 cm−1 and a net-gain cross section of 1.7 10−19 cm2 for the infrared laser line at 1062 nm. Different cavity configurations devoted to demonstrate the possibility of low threshold, high slope efficiency at 1062 nm, and efficient laser generation at 531 nm by self-frequency doubling are investigated for the ordinary and extraordinary beams.
We demonstrate the generation of 150-mW blue coherent single-mode
radiation at 457 nm in a compact and inexpensive setup. The light is
generated by frequency doubling the radiation of a master oscillator
power amplifier (MOPA) system in an enhancement cavity with a potassium
niobate (KNbO3) crystal. The MOPA consists of a 914-nm single-mode diode
laser and a broad-area diode laser (BAL) as the amplifier. The BAL is a
multimode laser with a specified wavelength of 938 nm. Sufficient gain
at 914 nm is obtained by antireflection coating the BAL front surface
and by cooling it to -10 °C.
A dual-wavelength continuous wave (CW) diode-pumped Nd:YAB laser that generates simultaneous laser action at the wavelengths 1062 and 1338 nm is demonstrated. A total output power of 278 mW at the two fundamental wavelengths was achieved at the absorbed pump power of 9.8 W. Furthermore, generation of yellow laser light at 592 nm produced by Type-I self-sum-frequency-mixing of both fundamental waves is observed under non-optimal phase matching conditions. With a diode pump power of 9.8 W, TEM00 mode yellow laser at 592 nm of 37 mW is obtained. The power stability in 4 h is better than 3.3%. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Efficient and compact green-yellow laser output at 545 nm is generated by intracavity frequency doubling of a continuous-wave
(CW) diode-pumped Nd:LuVO4 laser at 1089 nm under the condition of suppressing the higher gain transition near 1066 nm. With 18.7 W of diode pump power
and the frequency-doubling crystal KTiOPO4(KTP), as high as 2.3 W of CW output power at 545 nm is achieved, corresponding to an optical-to-optical conversion efficiency
of 12.3%; the output power stability over 4 h is better than 5.4%.
Efficient continuous-wave (CW) intracavity frequency doubling of a diode-end-pumped Nd:GdVO4 laser operating on 4F_(3/2)-4I_(9/2) transitions at 912 nm has been demonstrated. A symmetrical cavity with two laser rods is designed, which divides the pump power between the two laser rods, allowing for greater power scalability. An 18-mm-long BiBO crystal, cut for critical type I phase matching, is used for the intracavity frequency-doubled laser. A maximum output power of 6.2 W in the blue spectral range at 456 nm has been achieved with the pump power of 36 W. The beam quality M2 value is 2.5 in both horizontal and vertical directions. The ellipticity of the deep blue laser is 0.98, and the power stability is better than 3.2% at the maximum output power.
We report widely tunable infrared and self-frequency-doubled operation in ytterbium-doped yttrium aluminum borate (Yb:YAB). In the infrared, tuning has been obtained between 1016 and 1090 nm and also near 1125 nm. A tuning range at the 1-W level of 55 nm has been obtained. As a self-frequency-doubled laser, green output powers of 65 mW at 510 nm and over 450 mW at 530 nm have been demonstrated with a maximum diode-to-green conversion efficiency of 5%. Yb:YAB has been shown to cover the wavelengths of the copper-vapor (510 nm), argon-ion (514 nm), doubled Nd:YAG (532 nm), green HeNe (543 nm), and the doubled Yb:Sr5(VO4)3F laser in the visible (~565 nm).
We present for the first time a Nd:YVO4 laser emitting at 1064 nm intracavity pumped by a 916 nm diode-pumped Nd:LuVO4 laser. A 809 nm laser diode is used to pump the Nd:LuVO4 crystal emitting at 916 nm, a Nd:YVO4 laser crystal was pumped at 916 nm and lased at 1064 nm. Intracavity sum-frequency mixing at 916 and 1064 nm was then realized
in a LiB3O6 (LBO) crystal to reach the blue range. We obtained a continuous-wave output power of 216 mW at 492 nm under 19.6 W of incident
pump power at 809 nm.
We report a laser architecture to obtain continuous-wave blue radiation at 488 nm. A 808 nm diodepumped the Nd:YVO4 crystal emitting at 914 nm. A part of the pump power was then absorbed by the Nd:YVO4 crystal. The remaining was used to pump the Nd:YLF crystal emitting at 1047 nm. Intracavity sum-frequency mixing at 914 and
1047 nm was then realized in a LBO crystal to reach the blue radiation. We obtained a continuous-wave output power of 514
mW at 488 nm with a pump laser diode emitting 19.6 W at 808 nm.
A compact, efficient yellow-orange light at 593.5 nm was realized by the intracavity sum-frequency mixing using a BIBO crystal
in a diode-pumped Nd:YVO4 laser. At an incident pump power of 3.5 W, up to 126 mW of CW output light at 593.5 nm was achieved with a 1.5-mm-long critical
phase-matching BIBO. The optical-to-optical conversion efficiency was up to 3.6%, which was comparable to a 5-mm-long LBO.
The beam equality was excellent with an ellipticity of 0.97 and output noise of less than 0.8% (rms). Results confirm that
the BIBO is an efficient material for frequency conversion in the visible region.
The continuous-wave high-efficiency laser emission of Nd:GdVO4 at the second-harmonic of 456nm obtained by intracavity frequency doubling with an BiB3O6(BiBO) nonlinear crystal is investigated under pumping by diode laser at 880nm into emitting level 4F3/2. About 3.8W at 456nm with M2=1.4 was obtained from a 5mm-thick 0.4at.% Nd:GdVO4 laser medium and a 12mm-long BiBO nonlinear crystal in a Z-type cavity for 13.9W absorbed pump power. An optical-to-optical efficiency with respect to the absorbed pump power was 0.274. Comparative results obtained for the pump with diode laser at 808nm, into the highly-absorbing 4F5/2 level, are given in order to prove the advantages of the 880nm wavelength pumping.
A model describing forward and backward counter-propagating laser and second harmonic Gaussian waves inside a non-linear laser crystal is used to calculate the output green power obtained from the NYAB self-doubling laser. The model includes end-pumping, radially varying laser gain, beam waist data, walk-off effect and reabsorption of the second harmonic waves by the Nd3+ ions. The model is adjusted to fit experimental data from literature.
Laser oscillation in Nd:MgO:LiNbO3 has been demonstrated. Thresholds jas low as 3.6 mW and slope efficiencies up to 39% were achieved in a resonantly pumped miniature device. The electro-optical and nonlinear-optical properties of the host were also used to make active internal Q-switched and self-frequency-doubled lasers. Photorefractive damage is shown to be greatly suppressed compared with that for non-MgO-doped material. Absorption spectra, fluorescence spectra, and lifetime measurements are also reported.
Infrared laser action in Yb3+:YCOB (Yb3+:YCa4O(BO3)3) is reported for the first time. Maximum output powers of ∼300 mW with a slope efficiency of 35.8% have been obtained. The observation of self-frequency doubling in this material is also reported.
We report, for the first time to our knowledge, an acousto-optic Q-switched Er,Yb:YAl3(BO3)4 crystal laser operating in the 1.5–1.6 μm spectral region. The output characteristics of the lasers with different duty cycles, pulse repetition frequencies (PRF) and output couplers were investigated. The maximum single pulse energy of 91 μJ with the pulse width of 135 ns and the PRF of 5 kHz was achieved when the transmission of output coupler T = 1% and the duty cycle was optimized at 2.5%. The shortest pulse width of 90 ns was obtained at the PRF of 3 kHz for the transmission of output coupler T = 1.5%. The blue shift of laser emission and shortening of pulse width with reduction of PRF and increment of the pump power were observed. (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA) (© 2011 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
We investigate the output performance of the 1.06 μm4F3/2→4 I11/2 transition in Nd:GdVO4 and Nd:YVO4
thin-disk lasers under multi-pass pumping with diode lasers at 0.81 μm and at 0.88 μm, which corresponds to direct in-band pumping of the 4F3/2 emitting level. The use of a pump module with 24 passes through the crystal allowed the realization of an in-band pumped Nd:GdVO4 thin-disk laser with 14.9 W of continuous wave (cw) output power at 1.06 μm; the overall optical-to-optical efficiency was 0.50 and the slope efficiency
with respect to the incident pump power was 0.52. Intracavity frequency-doubling of the Nd:GdVO4 thin-disk laser with a LiB3O5 (LBO) nonlinear crystal yielded 9.1W of cw output power in the green at 0.53 μm with an overall optical-to-optical efficiency of 0.31.
We describe the output performances of the 916 nm 4F3/2 → 4I9/2 transition in Nd:LuVO4 under in-band pumping with diode laser at the 880 nm wavelength, directly into the 4F3/2 emitting level. An end-pumped Nd:LuVO4 crystal yielded 11.7 W of continuous-wave output power for 23.5 W of absorbed pump power. The slope efficiency with respect to the absorbed pump power was 66.6%. Furthermore, 5.9 W 458 nm deep-blue light was acquired by frequency doubling, resulting in an opticalto-optical efficiency with respect to the absorbed pump power of 25.1%. Comparative results obtained for the pump with diode laser at 809 nm, into the highly-absorbing 4F5/2 level, are given in order to prove the advantages of the in-band pumping. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
We report the efficient blue laser at 473 nm generation by intracavity frequency doubling of a continuous wave laser operation of a 885 nm diode direct pumped Nd:YAG laser on the 4F3/2 → 4I9/2 transition at 946 nm. A LiB3O5 (LBO) crystal, cut for critical type I phase matching at room temperature is used for second harmonic generation of the laser. At the absorbed pump power of 18.7 W, as high as 4.3 W of continuous wave output power at 473 nm is achieved with 15 mm long LBO. The optical-to-optical conversion efficiency with respect to the absorbed power is up to 0.23, and the beam quality M2 value is 1.2. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
We present for the first time laser architecture to obtain continuous-wave yellow radiation at 594 nm. The choice of crystals (Nd:LuVO4 for emission at 1343 nm and Nd:YAG for emission at 1064 nm) was guided by laser performance. A part of the pump power was then absorbed by the Nd:LuVO4 crystal, the remaining was used to pump the Nd:YAG crystal. Intracavity sum-frequency mixing at 1343 and 1064 nm was realized in a KTiOPO4 (KTP) crystal to reach the yellow radiation. We obtained a continuous-wave output power of 312 mW at 594 nm with a pump laser diode emitting 18.4Wat 808 nm. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
An efficient yellow-green laser at 559.6 nm based on the sum-frequency generation of diode-end-pumped Nd:YAG/SrWO4 Raman laser is demonstrated. The 45 mm in length SrWO4 crystal grown by Czochralski method and the KTP crystal with a type-II critical phase matching (θ = 83.4°, φ = 0°) cut were adopted for Raman conversion and sum-frequency generation, respectively. The maximum average power of 2.41 W was achieved at the incident pump power of 20.4 W and the pulse repetition rate of 60 kHz. The overall diode-yellow conversion efficiency was 11.8% and the slope efficiency was about 24%. The results show that the critical pump power of resonator instabiity is increasing with the pulse repe-tition rate. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Quasi continuous-wave (qCW) yellow emission (pulse duration 5 ms, repetition rate 20 Hz) at 559 nm is demonstrated through intracavity sum frequency generation (SFG) of Stokes and fundamental fields in Nd:YVO4 diode pumped self-Raman laser for the first time. Average in pulse output power at 559 nm was 0.47 W for 22 W of pump power, which corresponds to 2.1% of diode-to-yellow efficiency. The pulsed mode of operation was due to diode pump modulation and was used to reduce thermal stress of the crystal. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
A 8.2 W UV laser was reported with the compact extra-cavity sum-frequency mixing. The IR fundamental frequency source was a high power and high beam quality Q-switched Nd:YVO4 oscillator. 38Wfundamental frequency laser at 1064 nm was obtained at the pulse repetition rate of 450 kHz with the beam quality factors of M2x = 1.27, M2y = 1.21. The type I and type II phase-matched LBO crystals were used as the extra-cavity frequency doubling and mixing crystals respectively. At 38 kHz, 8.2 W UV laser at 355 nm was achieved with the pulse duration of 8 ns corresponding to the pulse peak power as high as 27 kW, and the optical-optical conversion efficiency from IR to UV was 25.6%. The output characteristics of the IR and the harmonic generations varying with the pulse repetition rate were also investigated detailedly. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
A new resonator design for doubly resonant continuous-wave (CW) cyan laser at 500.8 nm intracavity sumfrequency mixing in double-crystal RTP was reported. 392 mW of cyan laser at 500.8 nm was generated by mixing 1064 nm Nd:YVO4 laser and 946 nm Nd:YAG laser. The beam quality M2 value was equal to 1.5 in both horizontal and vertical directions at the maximum output power. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
We present a laser architecture to obtain continuous-wave (CW) light sources at the 589 nm sodium D2 line. A 808 nm diode-pumped a Nd:YLiF4 (Nd:YLF) crystal emitting at 1053 nm. A part of the pump power was then absorbed by the Nd:YLF crystal. The remaining was used to pump a Nd:YAG crystal emitting at 1338 nm. Intracavity sum-frequency mixing at 1053 and 1338 nm was then realized in a LiB3O5 (LBO) crystal to reach the yellow-orange radiation. We obtained a CW output power of 235 mW at 589 nm with a pump laser diode emitting 17.8 W at 808 nm. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
We present for the first time a Nd:YVO4 laser at 1085 nm intracavity pumped at 914 nm by a Nd:YVO4 laser. We obtained intracavity powers of 57 W at 914 nm and 62 W at 1085 nm. Using type-I critical phase-matching LiB3O5 (LBO) crystal, a cyan laser at 496 nm is obtained by 914 and 1085 nm intracavity sum-frequency mixing. The maximum laser output power of 142 mW is obtained when an incident pump laser of 19.6 W is used. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
We present for the first time a Nd:YAG laser emitting at 1064 nm intracavity pumped by a 946 nm diode-pumped Nd:YAG laser. A 809 nm laser diode is used to pump the first Nd:YAG crystal emitting at 946 nm, and the second Nd:YAG laser emitting at 1064 nm intracavity pumped at 946 nm. Intracavity sum-frequency mixing at 946 and 1064 nm was then realized in a LBO crystal to reach the cyan range. We obtained a continuous-wave output power of 485 mW at 501 nm with a pump laser diode emitting 25.4 W at 809 nm. (© 2010 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Nd:Ca4YO(BO3)3 (Nd:YCOB) crystal was grown by the Czochralski method, and its structure was measured by using a four circle X-ray diffractometer. The transparent spectrum from 200 to 2600 nm was measured at room temperature. The fluorescence spectrum near 1.06 μm showed that the main emission wavelength of Nd:YCOB crystal was centered at 1060.8 nm. Laser output at 1.06 μm has been demonstrated when it was pumped by a Ti:sapphire laser at the wavelength of 794 nm, the highest output power was 68 mW under pumping power of 311 mW, the pumping threshold was 163 mW and slope efficiency was 46.9%. The self-frequency doubled green light has been observed when it was pumped by a Ti:sapphire or a laser diode (LD). A 14.5 mm Nd:YCOB crystal sample cut at (θ, φ)=(90°, 33°) was used for type I second-frequency generation (SHG) of the 1.06 μm laser pulse. The SHG conversion efficiency was 22%.
Progress in the growth of the rare earth calcium oxyborate crystals has now generated a new class of laser materials that can be used as both a laser host and a nonlinear frequency converter. Laser action and self-frequency doubling (SFD) has been observed with both 10% and 20% Yb3+-doped YCOB crystals. Laser operation was obtained in a hemispherical linear cavity, end-pumped with a tunable cw Ti:Sapphire or a 980 nm laser diode pump source. Under Ti:Sapphire pumping at 900 nm, an output power of 230 mW and a slope efficiency of 29% was obtained using the 10% doped sample. Laser action was seen at 1050 nm. Laser operation of the 20% sample had a maximum output power of approximately 300 mW with a slope efficiency of 35.8% at 1088 nm. Laser action was not obtained at the peak of the fluorescence emission (approximately 1030 nm) in this crystal as a consequence of self-absorption on the short-wavelength side of the emission band. Diode-pumped operation at the narrow absorption peak of 977 nm was achieved and early results show an improved slope efficiency of 34% in comparison to the 10% doped crystal under Ti:Sapphire pumping. We have also observed self-frequency doubling in Yb3+:YCOB. The 20% Yb3+:YCOB crystal used for this test was cut with a phase-matching angle of 36.22°. The self-frequency doubling efficiency was low due to the absence of any frequency selective elements in the cavity to narrow the linewidth of the fundamental emission. The SFD emission occurred at 543 nm.
We report for the first time a coherent radiation at 488 nm by intracavity sum-frequency generation of 914 nm Nd:YVO4 laser and 1047 nm Nd:YLF (Nd:YLiF4) laser. Blue laser is obtained by using a doubly folded cavity, type-I critical phase matching LBO (LiB3O5) crystal sum-frequency mixing. With total pump power of 32.2 W (13.4 W pump power for 1047 nm Nd:YLF laser and 18.8 W pump power for 914 nm Nd:YVO4 laser), TEM00 mode blue laser at 488 nm of 1.23Wis obtained. The power stability in 30 min is better than 2.8%. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
We present what is, to the best of our knowledge, the first pulsed deep-blue laser at 456 nm by acousto-optical Q-switching and intracavity frequency doubling of a diode-endpumped Nd:GdVO4 laser on the 4F3/2 → 4I9/2 transition at 912 nm. When the incident pump power is 36 W, the maximum single pulse energy of 44.1 μ J, pulse duration of 140 ns and peak power of 315 W are achieved at 10 kHz; the maximum average power of 770 mW, pulse duration of 200 ns and peak power of 193 W are obtained at 20 kHz. The fluctuation of the blue output power is less than 2.4% within the given 20 min at the maximum blue output power. (© 2008 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
The quasi-three-level 912 nm continuous-wave laser emission under direct diode laser pumping at 880 nm into emitting level 4F3/2 of Nd:GdVO4 have been demonstrated. An endpumped Nd:GdVO4 crystal yielded 8.1 W of output power for 13.9 W of absorbed pump power. The slope efficiency with respect to the absorbed pump power was 0.679. To the best of our knowledge this is the first demonstration of such a laser system. Comparative results obtained for the pump with diode laser at 808 nm, into the highly-absorbing 4F5/2 level, are given in order to prove the advantages of the 880 nm wavelength pumping. (© 2009 by Astro Ltd., Published exclusively by WILEY-VCH Verlag GmbH & Co. KGaA)
Results on green laser performances are reported for a new efficient self-frequency-doubling (SFD) oxoborate crystal: Nd3+:Ca4GdO(BO3)(3) (Nd:GdCOB). 21 mW of green cw laser emission for an absorbed pump power of 820 mW were achieved under laser diode-pumping. 64 mW of green cw laser output were obtained with 1 W of absorbed pump power under titaniurn-sapphire pumping. Its availability in large-size crystals with good optical quality makes Nd:GdCOB a true challenger to the best SFD laser crystal reported so far: Nd:YAl3(BO3)(4) (Nd:YAB or NYAB).
We report the observation of coherent emission from three rare‐earth ions in electro‐optic crystals. Oscillation is observed from Nd<sup>3+</sup> ions in Bi 4 Ge 3 O 12 , LiNbO 3 , and Ba 0.75 Ca 0.25 Nb 26 O at room temperature, and from Tm<sup>3+</sup> and Ho<sup>3+</sup> ions in LiNbO 3 at 77°K. Second‐harmonic radiation is obtained from LiNbO 3 :Tm<sup>3+</sup> and electric‐field modulation of threshold is observed for certain crystals of LiNbO 3 :Nd<sup>3+</sup>. The latter effect is believed to arise from crystal strain. The propagation angle for phase‐matched second‐harmonic generation is calculated to lie at 43° to the c axis for both LiNbO 3 :Tm<sup>3+</sup> and LiNbO 3 :Ho<sup>3+</sup> at 77°K. Phasematched second‐harmonic generation from LiNbO 3 :Nd<sup>3+</sup> is not possible, since the maser line is an extraordinary wave. However, the polarization of the maser line in LiNbO 3 :Nd<sup>3+</sup> is appropriate for phasematched parametric frequency conversion in the near infrared. Attempts to observe such radiation were not successful due to the limited power available in the fundamental.
Laser radiation corresponding to the three fundamental colors (red, green, and blue) has been generated from the same Nd:YAl <sub> 3 </sub> (BO <sub> 3 </sub> ) <sub> 4 </sub> crystal, operating on a fundamental laser wavelength of 1338 nm in an end-pumping configuration. Continuous wave generation was obtained by pumping with a tunable Ti: sapphire laser. Red (669 nm) has been obtained by self-frequency doubling of the fundamental laser line. Green (505 nm) and blue (481 nm) have been obtained by self-sum-frequency mixing of the fundamental laser radiation at 1338 nm and the pump radiation (807 nm for green and 755 nm for blue). © 1999 American Institute of Physics.
We report efficient, diode-pumped, self-frequency doubling (SFD) in the newly developed laser crystal Nd <sup> 3+ </sup> :YCa <sub> 4 </sub> O(BO <sub> 3 </sub> ) <sub> 3 </sub>. More than 350 mW of fundamental output power at 1060 nm was achieved with a slope efficiency of 51%. With one watt of absorbed pump power, 62 mW of green cw laser emission at 530 nm was observed with proper phase matching. This initial performance, and the good optical properties of the crystalline host, are encouraging for the development of a high power diode-pumped SFD visible light laser source. © 1999 American Institute of Physics.
Gadolinium calcium oxoborate, Ca4GdO(BO3)3 (GdCOB), is an efficient nonlinear borate crystal presenting suitable sites for activator ions. Nd3+ doped GdCOB has been investigated as a new laser crystal in order to develop a self-frequency doubling material. Large and good optical quality crystals of Nd:GdCOB have been grown from the melt. Nd3+ optical properties were studied via Judd-Ofelt analysis. Nd3+ polarized absorption and emission cross sections were measured at room temperature. Stark levels of Nd3+4Lj manifolds in GdCOB are given. Nd:GdCOB laser has been demonstrated, with a cw Ti:sapphire pump source, for several Nd3+ concentrations. The crystal was shown to lase along its three crystallophysic axes. The best slope efficiency is 45 % for the fundamental laser output at 1.060 μm. According to the infrared laser output polarization, configuration of Nd:GdCOB crystals, for type I self-frequency doubling in ZX and XY principal planes, were investigated. A 0.530 μm green laser was observed by self-frequency doubling. Linear and nonlinear optical properties of Nd:GdCOB are compared to those of NYAB in the prospect of self-frequency doubling applications.
Ca4GdO(BO3)3 (GdCOB) is a new non-linear optical (NLO) material which presents a congruent melting and can be grown from the melt in large size crystals (φ=50 mm, L=120 mm) using the Czochralski pulling method. This paper describes the crystal growth and NLO properties of GdCOB which compare favorably with those of commercial borates like BBO or LBO. Particular emphasis will be put on SHG of the Nd:YAG 1.064 μm laser emission. Large amounts of Nd or Yb ions can be substituted for Gd in this material and Ln:GdCOB with Ln=Nd, Yb exhibits interesting laser properties, especially in the case of diode pumped Yb activated crystals. Finally by combining the NLO properties of the GdCOB matrix and the laser emission associated with the active ion, a green self frequency-doubling laser is obtained. In this field, Nd:GdCOB appears the most promising material for practical applications, able to generate visible green laser light with only one single crystal instead of two, as usually. To date an Nd:GdCOB crystal yields 114 mW at 530.5 nm (for 1250 mW of absorbed pump power), when pumped with a 2 W high brightness laser diode.
GdCOB (Ca4GdB3O10) is a new non-linear optical material which can be grown in large sized crystals by the Czochralski method. In this material, part of the gadolinium ions can be replace by Nd3+ without significant decrease of the crystal quality. Nd:GdCOB single crystals exhibit laser action in the infrared at 1060 and 1091 nm simultaneously. The two transitions involved originating from the two Kramers doublets of the 4F3/2 state, their respective contributions depend upon the temperature of the Nd:GdCOB crystal. By combining the non-linear properties of the GdCOB matrix and the laser emission due to ND3+ ions, it is possible to generate directly by self-frequency doubling 115 mW of green laser light at 530.5 nm under diode pumping at 810 nm. It is also possible to self-double the 936 nm emission of Nd:GdCOB, leading to blue laser emission, but only under pulsed titanium-sapphire laser pumping. However, a CW blue laser beam is obtained in Nd:GdCOB by self sum-frequency mixing of the 1090 nm laser emission and the residual pump beam at ∼812 nm, yielding 1.2 mW of 465 nm laser light, with an optical to optical efficiency of 0.3%. This paper ends with a survey of the Nd:YCOB laser characteristics which are compared to those of Nd:GdCOB.
As a new self-frequency doubling crystal, Nd:YCOB demonstrates a great potential for diode-pumped cw visible solid state lasers in a simple hemispherical cavity. We previously reported 62 mW cw green output with less than 1 W diode pump power absorbed in the crystal. Now we present more than 16 mW red cw laser at 666 nm from 5% Nd:YCOB crystal. As far as we know, it is the first time that diode-pumped cw red lasing is achieved by self-frequency doubling. Our effort on blue laser is also addressed.
We report for the first time (to our knowledge) cw orange-yellow emission at 589 nm from a compact double-end diffusion-bonded Nd(3+):LuVO(4) self-Raman laser with intracavity frequency doubling in LiB(3)O(5), pumped by an 880 nm diode laser. A 3.5 W cw orange-yellow emission with an overall diode-to-visible conversion efficiency of 13.3% is achieved through the use of an 18-mm-long double-ended diffusion-bonded Nd(3+):LuVO(4) crystal. The M(2) factors are 1.35 and 1.74 in both the horizontal and vertical dimensions, respectively.
We report a continuous-wave (cw) single frequency Nd:YAG blue laser at 473 nm end-pumped by a laser diode. A ring laser resonator was designed, the frequency doubling efficiency and the length of nonlinear crystal were optimized based on the investigation of the influence of the frequency doubling efficiency on the thermal lensing effect induced by energy-transfer upconversion. By intracavity frequency doubling with PPKTP crystal, an output power of 1 W all-solid-state cw blue laser of single-frequency operation was achieved. The stability of the blue output power was better than +/- 1.8% in the given four hours.
We report on a diode-pumped Nd:YAG laser with 4.6 W of linear polarized continuous-wave (cw) output power on the 4F3/2 --> 4I9/2 transitions at 946 nm. Three different crystals, cut for critical type I phase matching at room temperature, are used for the intracavity frequency doubling of the laser: 10-mm-long LiBaO5 (LBO), an 8-mm-long beta-BaB2O4 (BBO), and a 10.4-mm-long BiB3O6 (BiBO) grown by FEE GmbH. Up to 2.8 W of cw output power in the blue spectral range at 473 nm has been achieved with the BiBO crystal (2.1 W with BBO and 1.5 W with LBO).
Continuous-wave 457 blue laser emission at powers as high as 4.6 W is achieved by using a fiber-coupled laser diode array with a power of 30 W to pump 0.1 at. % low-doped bulk Nd:YVO4 crystal, with intracavity frequency doubling in a 15 ram long type I critical phase-matched LiB3O5 (LBO) crystal in a compact threefold cavity with a length of less than 100 mm. The optical-optical conversion efficiency is greater than 15.3%, and the stability of the output power is better than 3% for an hour. (c) 2006 Optical Society of America.