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Neodymium-doped Laser Gain Media

Definition: laser gain media containing laser-active neodymium ions

More general term: solid-state laser gain media

German: Neodym-dodierte Verstärkermedien

Categories: article belongs to category optical materials optical materials, article belongs to category laser devices and laser physics laser devices and laser physics


Cite the article using its DOI: https://doi.org/10.61835/xxh

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Neodymium (chemical symbol: Nd) is a chemical element belonging to the group of rare earth metals. In laser technology, it is widely used in the form of the trivalent ion Nd3+ as the laser-active dopant of gain media based on various host materials, including both crystals and glasses.

The usual pump wavelength is 808 nm (for Nd:YAG; wavelengths for other host materials can somewhat differ), but a higher slope efficiency can be achieved by direct pumping into the upper laser level 4F3/2 with 869-nm light (which is sometimes called in-band pumping, although this is quite accurate). The strongest laser transition is that from 4F3/2 to 4I11/2 for 1064 nm, but other transitions are available with longer or shorter wavelengths (see Figure 1). In order to achieve lasing on those, lasing at the 1064-nm line needs to be suppressed by inserting an appropriate wavelength filter (usually consisting of one or more dichroic mirrors) into the laser resonator. Via multi-phonon emission, the populations in levels 4I11/2 to 4I15/2 are quickly transferred to the ground-state manifold 4I9/2. (The lower-state lifetime is much smaller than the upper-state lifetime.) Hence, there is normally negligible population in all these levels, so that neodymium-doped gain media exhibit pure four-level behavior. The exception is the case where the lower level is the ground-state manifold 4I9/2: 946-nm Nd:YAG lasers (and other Nd-based lasers emitting between 900 and 1000 nm) are quasi-three-level lasers, exhibiting a fairly high threshold pump power.

energy level structure of the trivalent neodymium ion in Nd^{3+}:YAG
Figure 1: Energy level structure of the trivalent neodymium ion (with wavelength numbers for Nd:YAG).

For high excitation densities, as can occur particularly in Q-switched lasers, but also in lasers operating on the weaker laser transitions, there can be significant energy losses due to energy transfer (→ upconversion) to higher-lying levels with small lifetimes.

Overview on Neodymium-doped Gain Media

The most common neodymium-doped gain media are:

Less common neodymium-doped gain media are:

  • Nd:GdVO4 (gadolinium vanadate) for 1064 and 1341 nm: similar to Nd:YVO4, but having a larger gain bandwidth
  • Nd:GDD (gadolinium gallium garnet): used for high-power heat capacity lasers
  • the tungstates Nd:KGW = Nd:KGd(WO4)2 and Nd:KYW = Nd:KY(WO4)2: birefringent, large gain bandwidth, large Raman cross-sections
  • Nd:YALO = Nd:YAlO3 for 1079 and 930 nm: birefringent
  • Nd:YAP = Nd:YAlO3 for 1079 or 1340 nm: high thermal conductivity, birefringent
  • Nd:LSB = Nd:LaSc3(BO3)4 for 1062, 905 and 1348 nm: birefringent; allows very high neodymium concentration
  • Nd:S-FAP = Nd:Sr5(PO4)3F for 1059, 923 and 1328 nm: birefringent

In all these media (except for some glasses), the neodymium dopant ions replace other ions (often yttrium) of the host medium which have about the same size.

Neodymium-doped gain media face competition from ytterbium-doped media in the 1-μm spectral region. Those have a smaller quantum defect, usually a higher emission bandwidth and a higher upper-state lifetime, also a simpler energy level structure which avoids various quenching processes. However, they exhibit quasi-three-level behavior, which tends to lead to a higher threshold pump power, so that the power efficiency is not necessarily better than for neodymium-doped media.

More to Learn

Encyclopedia articles:


The RP Photonics Buyer's Guide contains 60 suppliers for neodymium-doped laser gain media. Among them:


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[13]Y. Sato and T. Taira, “The studies of thermal conductivity in GdVO4, YVO4, and Y3Al5O12 measured by quasi-onedimensional flash method”, Opt. Express 14 (22), 10528 (2006); https://doi.org/10.1364/OE.14.010528
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