Page 24 - Handbook of Lasers

Section 1.1
CRYSTALLINE PARAMAGNETIC ION LASERS

1.1.1 Introduction
The elements that have been reported to exhibit laser action as paramagnetic ions
(incompletely filled electron shells) in crystalline hosts are indicated in the periodic table of
the elements in Figure 1.1.1. These are mainly transition metal and lanthanide group ions
and generally involve intraconfigurational transitions. Typical concentrations of the lasing
ion are £1%; however, for some hosts and ions concentrations up to 100%, so-called
stoichiometric lasers, are possible. Also included in italics in Figure 1.1.1 are several ions
for which only gain has been reported (see Section 1.1.8).

Energy level diagrams and lasing transitions for iron group ions are shown in Figures
1.1.2 and 1.1.3, for divalent lanthanide and trivalent actinide ions in Figure 1.1.4, and for
trivalent lanthanides in Figures 1.1.5–1.1.9. The properties of lasers comprising these ions
are listed in Sections 1.1.4–1.1.6.

The general operating wavelengths of crystalline lanthanide-ion lasers are given in Figure
1.1.10 and range from 0.17 mm for the 5dfi 4f transition of Nd 3+ to 7.2 mm for the 4ffi 4f
transition between J states of Pr 3+ . Whereas ffi f transitions of the lanthanide ions have
narrow linewidths and discrete wavelengths, dfi f transitions of these ions and transitions of
many iron group ions have broad emission and gain bandwidths and hence provide a degree
of tunability. The tuning ranges of several paramagnetic laser ions in different hosts are
shown in Figure 1.1.11; the ranges for explicit host crystals are included in the laser tables.
Tunable lasers are based almost exclusively on vibronic transitions of iron transition group
elements.

Figure 1.1.1 Periodic table of the elements showing the elements (shaded) that have been
reported to exhibit laser action as paramagnetic ions in crystalline hosts. Gain has been reported
for elements shown in italics.

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