Spontaneous Recombination, Gain and Refractive Index Variation for 1.6 µm Wavelength InGaAsP/InP Lasers

The spontaneous carrier lifetime τ s was measured as a function of temperature for 1.6 µm wavelength InGaAsP/InP lasers. As a good approximation 1/τ s ∝ I th 1/2 , where I th is the threshold current, in the temperature region from 140 K to 320 K. The measured lifetime, given by τ s =1/( B eff N ), where N is the carrier density, resulted in the effective recombination coefficient B eff =1 –2×10 -10 cm 3 s -1 at room temperature. Gain spectra were measured for different temperatures. The gradient of room temperature peak gain with respect to carrier density was determined to be 1.2×10 -16 cm 2 . At 140 K this gradient as well as the curvature of the gain spectra showed an ∼10 times increase. The refractive index variation with carrier density was also obtained at different temperatures.