Neodymium-doped yttrium orthovanadate

Nd:YVO₄ in a frequency-doubled green laser pointer. Internal construction is shown. AAA-type cells and electronics lead to a laser module (enlarged in lower diagram). This contains a powerful 808 nm IR diode laser that pumps a Nd:YVO₄ laser crystal, in turn providing 1064 nm light. This immediately is doubled inside a nonlinear optics KTP crystal, resulting in green light at the half-wavelength of 532 nm. This beam is expanded and infrared-filtered.

Neodymium-doped yttrium orthovanadate (Nd:YVO₄) is a crystalline material formed by adding neodymium ions to yttrium orthovanadate. It is commonly used as an active laser medium for diode-pumped solid-state lasers. It comes as a transparent blue-tinted material. It is birefringent, therefore rods made of it are usually rectangular.

As in all neodymium-doped laser crystals, the lasing action of Nd:YVO₄ is due to its content of neodymium ions, which may be excited by visible or infrared light, and undergo an electronic transition resulting in emission of coherrent infrared light at a lower frequency, usually at 1064 nm (other transitions in Nd are available, and can be selected for by external optics).

Basic properties

• Atomic density: ~1.37×10²⁰ atoms/cm³

• Crystal structure:
  • zircon tetragonal (tetragonal bipyramidal)
  • space group D_4h
  • a=b=7.12, c=6.29

• Density: 4.22 g/cm³

• Mohs hardness: Glass-like, ~5

• Thermal expansion coefficient:
  • α_a=4.43×10⁻⁶/K
  • α_c=11.37×10⁻⁶/K

• Thermal conductivity:
  • parallel to C-axis: 5.23 W·m⁻¹·K⁻¹
  • perpendicular to C-axis: 5.10 W·m⁻¹·K⁻¹

Optical properties

• Lasing wavelengths : 914 nm, 1064 nm, 1342 nm

• Crystal class : positive uniaxial, n_o=n_a=n_b, n_e=n_c,
  • n_o=1.9573, n_e=2.1652, at 1064 nm
  • n_o=1.9721, n_e=2.1858, at 808 nm
  • n_o=2.0210, n_e=2.2560, at 532 nm

• Fluorescence lifetime (spontaneous emission lifetime) as a function of Nd ions concentration:

Nd concentration (atom %)	Fluorescence lifetime (μs)@ 1064 nm	Reference
0.4	110	J. Appl. Phys. 49, 5517-5522 (1978).
1.0	100	Castech web site
1.1	90	Casix web site
2.0	50	Casix web site

• Absorption cross-section at 808 nm : 5.5×10⁻²⁰ cm²

• Emission cross-section at 1064 nm : 38×10⁻¹⁹ cm² (Reference: JOSA 66, 1405-1414 (1976).)

• Polarized laser emission : π-polarization; parallel to optic axis (c-axis) (for a-cut crystal)

• Gain bandwidth : 0.96 nm (257 GHz) at 1064 nm (for 1.1 atm% Nd doped)

• Absorption coefficients at 808 nm for different doping conenctrations:

See also

• Yttrium aluminium garnet (YAG)

References

• H. E. Rast, H. H. Caspers, and S. A. Miller (1968). "Infrared Spectral Emittance and Optical Properties of Yttrium Vanadate" (abstract). Phys. Rev. 169 (3): 705–709. Bibcode 1968PhRv..169..705R. doi:10.1103/PhysRev.169.705. http://link.aps.org/abstract/PR/v169/p705. 
• O. Guillot-Noel, B. Bellamy, B. Viana, D. Gourier (1999). "Correlation between rare-earth oscillator strengths and rare-earth–valence-band interactions in neodymium-doped YMO4 (M=V, P, As), Y3Al5O12, and LiYF4 matrices" (abstract). Phys. Rev. B 60 (3): 1668–1677. Bibcode 1999PhRvB..60.1668G. doi:10.1103/PhysRevB.60.1668. http://link.aps.org/abstract/PRB/v60/p1668.