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Nd: YVO4

Related link: Nd: YVO4 Crystal Components  

 

Nd:YVO4 Crystal 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)

 ThermalExpansion 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

 

Nd:YVO4 Crystal 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(1% Nd doping)

 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 (λ in um)

 n02=3.77834+0.069736/(λ2-0.04724)-0.010813λ2

 ne2=4.59905+0.110534/(λ2-0.04813)-0.012676λ2

 

Nd: YVO4 Crystal absorption curve

 

Nd:YVO4 Crystal Laser Properties:

 

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 Nd:YVO4 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, Nd:YVO4 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 (ηs).

 

 

 Laser Crystal

Doping

(atm%)

σ

α

τ

Lα

Pth

ηs

(x10-19cm2)

(cm-1)

(μs)

(mm)

(mW)

(%)

 Nd:YVO4(a-cut)

1.0

25

31.2

90

0.32

30

52

2.0

25

72.4

50

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

 

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 the 2x2x5mm KTP and 3x3x1mm Nd:YVO4.