Homojunction lead-tin-telluride diode lasers with increased frequency tuning range

Homojunction lead-tin-telluride (Pb
1-x
Sn
x
Te) diode lasers with a CW frequency tuning range of 216 cm
^-1
(near
\lambda = 8 \mu
m) were fabricated from a Te-rich, ingot-nucleated crystal. The increased frequency tuning range is attributed to a reduced threshold Current density, which allows a higher operating temperature. At a heat-sink temperature of 11.2 K, the threshold current density (J
th
) is 212 A cm
^-2
. The highest heat-sink temperature recorded for these lasers is 61 K with a corresponding J
th
of
1.75 \times 10^{3}
A cm
^-2
. The longest, continuous current tuning (at 17 K) of one mode is 2.4 cm
^-1
. At a constant current, the temperature tuning of the same mode is 0.9 cm
^-1
. The lasers generally emit a single mode for current levels below 125 percent of J
th
. Single-mode, single-ended output powers up to 0.9 mW have been recorded.