Longitudinal Optical Phonon Resonating Dipole Radiation from Metal-Semiconductor Composite Structures and Quantum Interference

Longitudinal optical (LO) phonon resonant THz absorption and emission are observed using metal-semiconductor surface stripe structures, where electric dipoles are induced by interface polarization charges. The emission spectrum is affected by the stripe structures, while the peak position is independent. Further, quantum interference of two LO phonon modes and electronic intervalence band transition is found for alloy semiconductors. The present results indicate the feasibility of electro-magnetically induced transparency for optical gain based on LO phonon modes using this composite material.