Tunable infrared solid-state laser materials based on Cr3+in low ligand fields

A new class of solid-state tunable lasers based on Cr
³⁺
in low ligand field materials is described. Spectroscopic and calculated laser properties have been obtained for the
⁴
T
2
emission in two low field crystals: K
2
NaSc
1-x
Cr
x
F
6
and Al
1-x
Cr
x
(PO
3
)3. A comparison is made with two d
³
laser materials (Cr
³⁺
: alexandrite and V
²⁺
:MgF
2
. The prospect of expanding this class of materials is assessed.