Nd:YAG (neodymium-doped yttrium aluminum garnet; Nd:Y3Al5O12)
is the most commonly used laser crystal in solid-state lasers
because of its beneficial characteristics: it serves as a
four-level laser gain medium, has a long fluorescence lifetime,
a large stimulated emission cross-section, excellent thermal
conductivity, good mechanical strength, a high damage
threshold, low optical loss, and high pump efficiency.
Laser operation of Nd:YAG was first demonstrated by Joseph E. Geusic
[de] et al. at Bell Laboratories in 1964. Geusic and LeGrand Van Uitert
received the Optical Society of America's R. W. Wood Prize in 1993 "for
the discovery of the Nd:YAG laser and the demonstration of its usefulness
as a practical solid state laser source".
A cycle of sixty years has passed since its advent, Nd:YAG continues
to occupy a leading position in construction of solid-state lasers.
Applications of Nd:YAG lasers include: medicine, dentistry, manufacturing,
fluid dynamics, biophysics, auotmotive, military, among others.
Nd:YAG Absorption Spectra
Nd:YAG Emission Spectra
Properties of Nd:YAG Crystal
Chemical Formula:
Nd:Y3Al5O12
Crystal Structure:
Cubic
Lattice Parameter:
12.01 Å
Density:
4.55 g/cm3
Melting Point:
1970 °C
Mohs Hardness:
8.5
Thermal Expansion Coefficient:
14 W/m /K @20°C, 10.5 W /m /K @100°C
Optical Properties
Refractive Index:
1.82 @1064nm
Lasing Wavelength:
1064 nm, 946nm, 1318nm
Stimulated Emission Cross Section:
2.8 x 10-19 cm²
Relaxation Time of Terminal Lasing Level:
30 ns
Radiative Lifetime:
550 µs
Spontaneous Fluorescence:
230 µs
Loss Coefficient:
0.003 cm-1 @ 1064 nm
Pump Wavelength:
807.5 nm, 868.4nm
Absorption band at pump wavelength:
1 nm
Linewidth:
0.6 nm
Polarized Emission:
Unpolarized
Thermal Birefringence:
High
Capability of Nd:YAG Laser Crystal
Nd dopant concentration:
> 0.6 ~ 1.3 atm%
Dopant tolerance:
within 10% of concentration
Diameter:
3 ~ 14 mm
Length:
1 ~ 160 mm
Anti-reflection coating:
R < 0.1% @ 1064 nm
High transmission coating:
T>95% @ 808 nm
High reflection coating:
R>99.8% @ 1064 nm
General Specifications of Nd:YAG Crystal
Dimension Tolerance:
+0/-0.1mm(WxH) and +0.1/-0.2mm thickness
Surface Quality:
10-5 Scratch-dig
Flatness:
<λ/8 @633nm
Wavefront Distortion:
λ/10 per inch
Chamfer:
0.1mm@45deg.
Clear Aperture:
Central 95%
Parallelism:
<10 arc seconds
Perpendicular:
<5 arc minutes
Orientation Angle:
<111> crystalline direction (+/-0.5°)
Damage Threshold:
over 15J/cm² (without coating), over 700 MW/cm² (coating)
Nd:YAG Absorption Spectra
Nd:YAG Emission Spectra
