Higher power semiconductor radiating mirror laser

DETAILED DESCRIPTION Referring now specifically to FIG.
1, there is shown an active element 10 of the type preferrably used in a radiating mirror laser embodying the invention.
The element 10 is fabricated from an alloy semiconductor compound of the type having a direct energy bandgap that can be increased or decreased by varying the relative composition of its constituents.
There are a wide variety of semiconductor compounds that exhibit this characteristic so that the particular compound selected for the element 10 will depend to a large extent upon the intended application of the laser (e.
g.
, the wavelength of operation desired).
Lead salt compounds such as Pb.
sub.
1-x Sn.
sub.
x Se, Pb.
sub.
1-x Sn.
sub.
x Te and quaternary and higher order alloys of these compounds are considered particularly attractive for obtaining laser emission over a wide range in the infrared.
Such compounds are also readily grown as high quality single crystals with excellent homogeneity by standard crystal growth methods (e.
g.
, the Bridgman method).
For purposes of illustration, the element 10 will be considered to be formed from Pb.
sub.
1-x Sn.
sub.
x Se.
FIG.
2 illustrates the variation of the bandgap of the illustrative material Pb.
sub.
1-x Sn.
sub.
x Se, as a function of x, the relative Sn composition.
The bandgap is expressed on the left hand vertical axis in electron volts (eV).
The upper curve 12 represents the behavior of the semiconductor at 77.
degree.
Kelvin (K.
) while the lower curve 14 represents the behavior of the semiconductor at 12.
degree.
K.
The wavelength of emission to which the bandgap corresponds is indicated on the right hand vertical axis in micrometers (.
mu.
m).
As can be appreciated from FIG.
2, the bandgap of Pb.
sub.
1-x Sn.
sub.
x Se decreases, while the wavelength increases, as x is increased.
Relatively small changes in x give rise to relatively large variations in wavelength.
In practice, it has been possible to grow Pb.
sub.
1-x Sn.
sub.
x Se crystals of sufficient quality for lasers with x values ranging from zero to about 0