Products>Waveplates Crystals>YVO4 Crystal |
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Neodymium
Doped Yttrium Orthvanadate (Nd:YVO4) Crystal |
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Nd:YVO4 is 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 high power, stable and cost-effective
diode pumped solid-state lasers. Recent developments have
shown that Nd:YVO4 can produce powerful
and stable IR, green, blue lasers with the design of Nd:YVO4 and frequency doubling crystals.
Compared with Nd:YAG
and Nd:YLF for diode laser pumping, Nd:YVO4 lasers possess the advantages of lower dependency
on pump wavelength and temperature control of a diode
laser, wide absorption band, higher slope efficiency,
lower lasing threshold, linearly polarized emission and
single-mode output. For the applications in which more
compact design and the single-longitudinal-mode output
are needed, Nd:YVO4 shows its particular
advantages over other commonly used laser crystals. The
diode laser-pumped Nd:YVO4 compact
laser and its frequency-doubled green, red or blue laser
will be the ideal laser tools of machining, material processing,
spectroscopy, wafer inspection, light show, medical diagnostics,
laser printing and the most widespread applications. |
With advanced technology on growing high optical quality
and large size Nd:YVO4 crystals, AZURE
steadily provides as large as f35x50 mm3 Nd:YVO4 bulk crystal and f20x20mm3 finished crystal
with very low intrinsic optical loss. Now, AZURE massively
produces and provides high quality Nd:YVO4 crystals at very competitive prices.
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Properties
Main Features:
- Low lasing threshold
and high slope efficiency
Large stimulated emission cross-section
at lasing wavelength
High absorption over a wide pumping wavelength
bandwidth
Optically uniaxial and large birefringence
emits polarized laser
1. Basic Properties
Atomic
Density: ~1.37x1020 atoms/cm2
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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:||C: 5.23 W/m/K; ^C: 5.10
W/m/K |
2. Optical Properties
(typically for 1.1 atm% Nd:YVO4, a-cut crystals)
Lasing
Wavelengths |
914nm,
1064 nm, 1342 nm |
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
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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
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Stimulated
Emission Cross-Section |
25.0x10-19 cm2 , @1064 nm
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Fluorescent Lifetime |
90 ms (about 50 ms for 2 atm% Nd doped) @ 808 nm
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Absorption
Coefficient |
31.4
cm-1 @ 808 nm |
Absorption
Length |
0.32
mm @ 808 nm |
Intrinsic
Loss |
Less
0.1% cm-1 , @1064 nm |
Gain
Bandwidth |
0.96
nm (257 GHz) @ 1064 nm |
Polarized
Laser Emission |
p polarization;
parallel to optic axis (c-axis) |
Diode
Pumped Optical to Optical Efficiency |
>
60% |
3. Absorption Curves
of Different Doping Nd:YVO4
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. Different doping levels
Nd:YVO4 are shown showed as follow
Absorption Curve of 0.5% doping YVO4
(Thickness:1 mm) |
Absorption Curve of 3% doping YVO4
(Thickness:1 mm) |
4. Fluorescence Spectra Curve
Normalized fluorescence spectra
from 800 nm to 1600 nm of Nd 1.1 at. % doped Nd:YVO4 for p polarization (a) and for s polarization (b).
5. Laser Properties
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 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(atm%) |
ó
(x10-19cm2)
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a
(cm-1) |
t
(ms) |
la
(mm) |
Pth
(mw) |
ηs
( %) |
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
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9.2 |
90 |
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231 |
45.5 |
Nd:YAG |
0.85 |
6
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7.1 |
230 |
1.41 |
115 |
38.6 |
Furthermore, the 1.34 mm
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.
Nd:YVO4 crystal has a low thermal
conductivity coefficient, therefore, long-in-length with low dopant level
Nd:YVO4 is recommended for high power diode laser application in order
to reduce thermal lasing effects. Gold metalization on the side of Nd:YVO4
crystals is the solutions not only for thermal lasing effects for high
power pumped, but also enhancing lasing mode of the laser. If you have
any questions, please ask AZURE salesmen for assistance. 6.
Diode Laser-Pumped Nd:YVO4 Lasers
- 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%.
- Recently, over 30 W of TEM00 output power was achieved by using a-cut Nd:YVO4
and pumped by 60 W fiber coupled diode lasers. The optical conversion
efficiency exceeds 50%. High power and stable infrared output @ 1064
nm and 1342 nm has been available with diode pumped Nd:YVO4
lasers.
- Single-longitudinal-mode
oscillation of a Nd:YVO4 microchip laser has been
achieved with high power and high slope efficiency. 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.
Basic Experimental
Scheme of Diode Laser Pumped Nd:YVO4 Green Laser
7. Frequency-doubled Nd:YVO4 Lasers
- 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 interactivity
KTP.
- Diode pumped green lasers
has been commercialized with the compact design of Nd:YVO4 + KTP crystals. 2.5 mW green output was achieved in
a Nd:YVO4 microchip laser with a very short (9
mm) laser cavity when pumped by a 50 mW diode laser.
- Over 10 W and high stable
CW green output @ 532 nm was commercially available with diode pumped
Nd:YVO4 and frequency double using NCPM LBO crystals.
Single longitudinal mode (SLM) green output, Q-switched green and
UV outputs were also obtained.
- Over 400 mW blue laser @
457 nm based on Nd:YVO4+ BBO crystals, is Comerica
available .
Standard
Specs and Note
Standard Specs. of AZURE's Nd:YVO4 Crystals
Nd:
Dopant Level |
0.1
- 3.0 atm% |
Standard
Dimensions |
3x3x3
mm3, 3x3x1 mm3, 3x3x0.5 mm3
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Wavefront
Distortion |
< l/8 at 633 nm |
Scattering
Sites |
invisible,
probed with a He-Ne laser |
Orientation |
±0.5
deg |
Dimensional Tolerance |
+0.1/-0.1
mm |
End-faces
Configuration |
Plano/Plano |
Surface
quality |
10/5
Scratch/Dig per MIL-O-13830B |
Flatness |
l/10 at
633 nm |
Clear
Aperture |
>
Central 90% |
Parallelism |
<
10 arc sec. |
Intrinsic
Loss |
<
0.1% cm-1 |
Note:Other specifications of Nd:YVO4 crystals
and coatings are available upon request.
AZURE provides the complete diode pumped laser kits, including
laser crystals (Nd:YVO4 and Nd:YAG), NLO crystals
(KTP) and laser optics. Please refer to DPSS laser kits for information
about diode pumped laser optics kits. |