| Neodymium
Doped Yttrium Orthovanadate (Nd:YVO4) |
 Nd:YVO4 is the most efficient
laser host crystal for diode pumping among the current commercial
laser crystals, especially, for low to middle power density.
This is mainly for its absorption and emission features surpassing
Nd:YAG. Pumped by laser diodes, Nd:YVO4 crystal
has been incorporated with high NLO coefficient crystals (LBO,BBO,or
KTP) to frequency-shift the output from the near infrared
to green, blue, or even UV. This incorporation to construct
all solid state lasers is an ideal laser tool that can cover
the most widespread applications of lasers, including machining,
material processing, spectroscopy, wafer inspection, light
displays, medical diagnostics, laser printing, and data storage,
etc. It has been shown that Nd:YVO4 based diode
pumped solid state lasers are rapidly occupying the markets
traditionally dominated by water-cooled ion lasers and lamp-pumped
lasers, especially when compact design and single-longitudinal-mode
outputs are required.
|
Nd:YVO4's
advantages over Nd:YAG
-
As high as about five
times larger absorption efficient over a wide pumping bandwidth
around 808 nm (therefore, the dependency on pumping wavelength
is much lower and a strong tendency to the single mode
soutput)
-
As large as three times larger
stimulated emission cross-section at the lasing wavelength of
1064nm
-
Lower lasing threshold
and higher slope efficiency
-
As a
uniaxial crystal with a large birefringence, the emission is only
a linearly polarized.
CASTECH Provides:
-
Various doping concentration
from 0.1% to 3%
-
Various size bulk and finished high quality
Nd:YVO4 crystals up to Φ35x50mm3 and Φ20x20mm3,
respectively;
-
10,000 pcs of Nd:YVO4 devices per
month in sizes 3x3x0.5 to 4x4x8 mm
-
With quick
delivery
- With competitive
price
Basic Properties:
| Atomic Density: |
1.26x1020 atoms/cm3
(Nd1.0%) |
| Crystal Structure: |
Zircon Tetragonal,
space group D4h-I4/amd
a=b=7.1193A,c=6.2892A |
| Density; |
4.22g/cm3 |
| Mohs Hardness: |
4-5(Glass-like) |
| Thermal Expansion Coefficient(300K): |
αa=4.43x10-6/K
αc=11.37x10-6/K |
| Thermal Conductivity
Coefficient(300K): |
//C:0.0523W/cm/K
⊥C:0.0510W/cm/K |
Optical Properties:
| Lasing wavelength: |
1064nm,1342nm |
| Thermal optical coefficient (300K): |
dno/dT=8.5×10-6/K
dne/dT=2.9×10-6/K |
| Stimulated emission cross-section: |
25×10-19cm2 @ 1064nm |
| Fluorescent lifetime: |
90μs |
| Absorption coefficient: |
31.4cm-1 @810nm |
| Intrinsic loss: |
0.02cm-1 @1064nm |
| Gain bandwidth: |
0.96nm@1064nm |
| Polarized laser emission: |
π polarization;
parallel to optic axis(c-axis) |
| Diode pumped optical
to optical efficiency: |
>60% |
| Sellemeier equations |
n02=3.77834+0.069736/(λ2-0.04724)-0.010813λ2
ne2=4.59905+0.110534/(λ2-0.04813)-0.012676λ2 |
Laser Properties
of Nd:YVO4
1. One of the most attractive
character of Nd:YVO4 is, compared with Nd:YAG, it has 5
times larger absorption coefficient in a broader absorption bandwidth
around the 808 nm peak pump wavelength, which just matches the standard
of high power laser diodes currently available. This means a smaller
crystal that could be used for the laser, leading to a more compact
laser system. For a given output power, this also means a lower power
level at which the laser diode operates, thus extending the lifetime
of the expensive laser diode. The broader absorption bandwidth of
Nd:YVO4 which may reaches 2.4 to 6.3 times that of Nd:YAG,
is also valuable. Besides more efficient pumping, it also means a
broader range of selection of diode specifications. This will be helpful
to laser system makers for wider tolerance and lower cost choice.
2. Nd:YVO4 crystal has larger stimulated
emission cross-sections, both at 1064nm and 1342nm. When a-axis cut
Nd:YVO4 crystal lasing at 1064m, it is about 4 times higher
than that of Nd:YAG, while at 1340nm the stimulated cross-section
is 18 times larger, which leads to a CW operation completely outperforming
Nd:YAG at 1320nm. These make Nd:YVO4 laser be easy to maintain
a strong single line emission at the two wavelengths.
3. Another important character of Nd:YVO4
lasers is, because it is an uniaxial rather than a high symmetry of
cubic as Nd:YAG, what it emits is only a linearly polarized, thus
avoiding undesired birefringent effects on the frequency conversion.
Although the lifetime of Nd:YVO4 is about 2.7 times shorter
than that of Nd:YAG, its slope efficiency can be still quite high
for a proper design of laser cavity, because of its high pump quantum
efficiency.
The major laser properties of Nd:YVO4 vs Nd:YAG are listed
in Table below, including stimulated emission cross-sections (σ),
Absorption Coefficient (α) Fluorescent lifetime (τ),Absorption Length
(La),threshold Power (Pth) and
Pump Quantum Efficiency (η).
Laser Properties of
Nd:YVO4 vs Nd:YAG
| LASER
CRYSTAL |
DOPING(ATM%) |
σ
(x10-19CM2) |
α
(CM-1) |
τ
(MS) |
Lα
(MM) |
PTH
(MW) |
ηs
(%) |
| Nd:YVO4(a-cut) |
1.0
2.0 |
25
25 |
31.2
72.4 |
90
50 |
0.32
0.14 |
30
78 |
52
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 |
Typical Results:
• Diode pumped Nd:YVO4
laser output comparing with diode pumped Nd:YAG laser.
| Crystals |
Size(mm3) |
Pump
Power |
Output (at 1064nm) |
| Nd:YVO4 |
3x3x1 |
850mW |
350mW |
| Nd:YVO4 |
3x3x5 |
15W |
6W |
| Nd:YAG |
3x3x2 |
850mW |
34mW |
• Diode pumped Nd:YVO4+KTP
green laser.
- 8W green laser was generated from
a 15W LD pumped 0.5% Nd:YVO4 with intracavity KTP.
- 200mW green outputs are generated
from 1W LD pumped 2% Nd:YVO4 lasers by using CASTECH's 2x2x5mm KTP and 3x3x1mm
Nd:YVO4
- 2-5mw green outputs are generated
from 180mw LD pumped 3% Nd:YVO4and KTP glued crystals.For more details,please
refer to Glued Crystals
CASTECH Warranty on Nd:YVO4 Specifications:
• Transmitting wavefront distortion:less than λ/4 @ 633nm
• Dimension tolerance:(W±0.1mm)x(H±0.1mm)x(L+0.2mm/-0.1)
• Clear aperture:>90% central area
• Flatness: λ/8 @ 633 nm, and λ/4 @ 633nm for thickness less
than 2mm
• Scratch/Dig code: 10/5 to MIL-O-13830A
• Parallelism:better than 20 arc seconds
• Perpendicularity: 5 arc minutes
• Angle tolerance:<±0.5°
• AR coating:R<0.2% at 1064nm,HR coating:R>99.8% at 1064nm,T>95%
at 808nm
• Quality Warranty Period:one year under proper use.
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