Gain measurements in 1.3 µm InGaAsP-InP double heterostructure lasers

The net gain per unit length (
G
) versus current (
I
) is measured at various temperatures for 1.3 μm InGaAsP-InP double heterostructure lasers.
G
is found to vary linearly with the current
I
at a given temperature. The gain bandwidth is found to decrease with decreasing temperature. The lasing photon energy decreases at 0.325 meV/K with increasing temperature. Also, the slope
dG/dI
at the lasing photon energies decreases with increasing temperature. This decrease is more rapid for
T > \sim210
K. This faster decrease is consistent with the observed higher temperature dependence of threshold (low T
0
at high temperatures) of 1.3 μm InGaAsP lasers. A carrier loss mechanism, due to Auger recombination, also predicts that
dG/dI
should decrease much faster with increasing temperature at high temperatures. We also find that the slope
dG/dI
decreases slowly with increasing temperature for a GaAs laser, which is consistent with the observed temperature dependence of threshold of these lasers.