Spectral hole burnings at high energy tails in spontaneous emission and hot carrier relaxation in InGaAsP lasers

Spectral hole burnings in spontaneous emission spectra from 1.3 μm InGaAsP lasers were found. The results are understood on the basis of population burnings of holes associated with the saturation of intervalence-band absorption. Theoretical results on hot carrier relaxation are shown to explain the population burnings, pointing out an importance of nonequilibrium optical phonon populations in the active layers of long wavelength InGaAsP lasers and light emitting diodes (LED's).