Laser-modulator compatibility in an InGaAs/InAlAs superlattice structure

An InGaAs/InAlAs p-i-n double heterostructure was grown on n-type InP substrate by MBE (molecular beam epitaxy). This structure was optimized for optical waveguide modulation based on Wannier-Stark localization. The intrinsic region contains a strongly coupled superlattice. The superlattice PL (photoluminescence) linewidth is 2.4 meV at 10 K, indicating very high material quality. Under reverse bias, Wannier-Stark localization was observed on photocurrent spectra up to room temperature. Both fundamental and oblique transitions are very sharp with strong excitonic behaviors. Optical waveguide modulation performances were characterized on a 100- mu m-long device operating under TE polarization mode. The performances obtained at phonon energy below the superlattice bandgap are illustrated. Although the structure was optimized for modulation, laser emission was observed under forward bias.<>