Temperature Dependence of Optical Gain and Loss in 2-$\mu$ m InP Lasers

Temperature-dependent optical gain, loss, and internal quantum efficiency have been measured for continuous-wave operated 2- μm InP laser from 10
^°
C to 70
^°
C using the Hakki-Paoli method. Modal gain and loss were extracted from the measured amplified spontaneous emission. The optical loss is constant with temperature, while the material gain decreases from 1128 cm
^-1
at 10
^°
C to 427 cm
^-1
at 70
^°
C. The internal efficiency decreases from 74% to 37% at 10
^°
C and 50
^°
C , respectively. The temperature sensitivity of threshold current is due to the decrease of the differential gain and a degradation of internal quantum efficiency.