Neodymium Doped Yttrium Orthvanadate Crystal
(Nd:YVO4)
CASIX has developed a new method to grow high optical quality and large size Nd:YVO4 crystals. As large as f35x50 mm3 Nd:YVO4 bulk crystal and f20x20mm3 finished crystal with very low intrinsic optical loss are steadily obtained. Now, CASIX massively produces and provides high quality Nd:YVO4 crystals at very competitive prices.
Nd:YVO4 has excellent features and it applied to many fields:
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Nd:YVO4 one of the most efficient laser host crystal currently existing for diode laser-pumped solid-state lasers. Its large stimulated emission cross-section at lasing wavelength, high absorption coefficient and wide absorption bandwidth at pump wavelength, high laser induced damage threshold as well as good physical, optical and mechanical properties make Nd:YVO4 an excellent crystal for the high power, stable and cost-effective diode laser-pumped solid-state lasers. Recent developments have shown that Nd:YVO4 micro-lasers can produce powerful and stable IR and green or red lasers with the design of Nd:YVO4 + KTP.
2. Basic Properties (typically for 1.1 atm%, a-cut Nd:doped YVO4 crystals)
| Atomic Density: | ~1.37x1020 atoms/cm2 |
| Crystal Structure: | Zircon Tetragonal, space group D4h, a=b=7.12, c=6.29 |
| Density: | 4.22 g/cm2 |
| Mohs Hardness: | Glass-like, ~5 |
| Thermal Expansion Coefficient: | aa=4.43x10-6/K, ac=11.37x10-6/K |
| Thermal Conductivity Coefficient: | ºC: 0.0523 W.cm/K; ÁC: 0.0510 W.cm/K |
| Lasing Wavelength: | 1.064 um, 1.342 um |
| Crystal class: | positive uniaxial, no=na=nb, ne=nc, |
| no=1.9573, ne=2.1652, @ 1064nm | |
| no=1.9721, ne=2.1858, @ 808nm | |
| no=2.0210, ne=2.2560, @ 532nm | |
| Sellmeier Equation (for pure YVO4 crystals): | |
| no2=3.77834+0.069736/(l2 - 0.04724) - 0.0108133.l2 | |
| ne2=4.59905+0.110534/(l2 - 0.04813) - 0.0122676.l2 | |
| Thermal Optical Coefficient: | dna/dT=8.5x10-6/K, dnc/dT=3.0x10-6/K |
| Stimulated Emission Cross-Section: | 25.0x10-19 cm2 @ 1.06 um |
| Fluorescent Lifetime: | 90 us (about 50 ms for 2 atm% Nd doped) @ 0.81 um |
| Absorption Coefficient: | 31.4 cm-1 @ 0.81 um |
| Absorption Length: | 0.32 mm @ 0.81 um |
| Intrinsic Loss: | 0.02 cm-1 @ 1.06 um |
| Gain Bandwidth: | 0.96 nm (257 GHz) @ 1.06 um |
| Polarized Laser Emission: | p polarization; parallel to optic axis (c-axis) |
| Diode Pumped Optical to Optical Efficiency: | > 60% |
Nd:YVO4 shows high absorption coefficients at pumping wavelengths. Therefore, a crystal short-in-length (e.g. 1mm) is preferred, and more compact lasers can be constructed by using Nd:YVO4 than using Nd:YAG. Furthermore, it has a wide and smoothly-varied bandwidth of absorption, so that it allows of less stringent requirements of diode laser selection and wavelength control as compared with Nd:YAG.
The Nd:YVO4 crystal has large stimulated emission cross-sections (s) at both 1.06 mm and 1.3 mm. The stimulated emission cross-section of an a-axis cut Nd:YVO4 crystal at 1.064mm is about 4 times that of the Nd:YAG crystal. Although the lifetime (t) of Nd:YVO4 is about 2.7 times shorter than that of Nd:YAG, a figure of merit (FOM) for minimum threshold of a-cut Nd:YVO4, which is proportional to the st products, is reasonably higher than that of Nd:YAG crystal. Because of its high pump quantum efficiency (hp), the slope efficiency of Nd:YVO4 can be very high if the laser cavity is properly designed. The following Table lists the major laser properties of Nd:YVO4 in comparison with those of Nd:YAG.
Laser properties of Nd:YVO4 crystals vs Nd:YAG
| Laser crystal | Nd doped | s | a | t | la | Pth | hs |
| (atm%) | (x10-19cm2) | (cm-1) | (us) | (mm) | (mw) | ( %) | |
| Nd:YVO4(a-cut) | 1.1 2.0 |
25 | 31.2 72.4 |
90 50 |
0.32 0.14 |
78 | 48.6 |
| Nd:YVO4(c-cut) | 1.1 | 7 | 9.2 | 90 | ¡¡ | 231 | 45.5 |
| Nd:YAG | 0.85 | 6 | 7.1 | 230 | 1.41 | 115 | 38.6 |
Furthermore, the 1.34 um CW operation of the Nd:YVO4 laser completely outperformed that of Nd:YAG at 1.32 mm because of an 18 times larger stimulated cross-section.
A threshold of 78 mW and a slope efficiency of 48.5% at 1.064 mm were obtained by using an a-cut 3 mm long Nd:YVO4 crystal with output coupler R = 96%. Under the same conditions, a 5 mm long Nd:YAG crystal has a threshold of 115 mW and a slope efficiency of 38.6%.
When a 1 mm long, a-cut Nd:YVO4 crystal was put into a 13 mm long laser cavity, 278 mW output at 1.064 mm was extracted from a 730 mW diode laser.
Recently, 13.8 W of TEM00 output power was reported by using a-cut Nd:YVO4 and pumped by 26 W laser diode array. The optical conversion efficiency is 53%.
Single-longitudinal-mode oscillation of a Nd:YVO4 microchip laser has been achieved with high power and high slope efficiency. Typically, a single-mode output of ~103 mW has been observed with ~5.3 mW CW threshold and over 32.4% slope efficiency. This microchip laser can be tuned over a wide range of frequencies (over 107 GHz), without mode hopping, by heating the laser crystal. Such a single mode source has been developed for the use of a master oscillator for injection locking of Nd laser systems.
Because of its large stimulated emission cross section at 1.34 mm, Nd:YVO4 is also an efficient laser crystal for diode laser-pumped 1.3 mm laser. By using 1 mm long Nd:YVO4 crystal and pumped by an 850 mW diode laser at 808 nm, 50 mW output at 1.34 mm has been observed, compared to 34 mW from 2 mm long Nd:YAG.
By using the compact design of Nd:YVO4 + KTP crystals, high power green or red light output can be generated in a diode laser pumped Nd:YVO4 laser. When pumped by a 890 mW diode laser, more than 76 mW single mode (TEM00) green output was obtained with a 3x3x1 mm3 Nd:YVO4 and a 3x3x5 mm3 intracavity KTP.
Recently, 2.5 mW green output was observed in a Nd:YVO4 micro-laser with a very short (9 mm) laser cavity when pumped by a 50 mW diode laser.
| Nd: Dopant Level: | 0.5 - 3.0 atm% |
| Standard Dimensions: | 3x3x3 mm3, 3x3x1 mm3, 3x3x0.5 mm3 |
| Wavefront Distortion: | < l/8 at 633 nm |
| Scattering Sites: | invisible, probed with a He-Ne laser |
| Orientation: | a-axis or c-axis cut, ¡À0.5 deg. |
| Dimensional Tolerance: | +0.2/-0 mm |
| End-faces Configuration: | Plano/Plano |
| Scratch/Dig Code: | 10/5 per MIL-O-13830A |
| Flatness: | l/10 at 633 nm |
| Clear Aperture: | > Central 90% |
| Parallelism: | < 10 arc sec. |
| Perpendicularity: | < 5 arc min. |
1. Other specifications of Nd:YVO4 crystals and coatings are available upon request.
2. CASIX provides KTP or LBO and BBO crystals for frequency-doubled and tripled Nd:YVO4 lasers.
3. Pure YVO4 crystals is an excellent birefringent crystal for polarizing elements from 0.5 to 5 mm region (see Page 51 and our Optics Guide 1996)
4. Er:YVO4 and Tm:YVO4 crystals are being developed in CASIX.
Copyright 1998 CASIX, Inc. All rights reserved.
Last Revised: October
20, 1998
Web Page maintained by : Contact@CASIX.com
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Properties of Nd:YVO4
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