Semiconductor–superlattice frequency multiplier for generation of submillimeter waves

We report on a semiconductor–superlattice frequency multiplier for the generation of submillimeter waves. A monochromatic microwave-pump field (frequency near 100 GHz) periodically excited a superlattice into states of negative differential conductivity giving rise to space-charge domain creation and annihilation joint with a nonsinusoidal high-frequency current and radiation at harmonics of the pump field. A highly doped GaAs/AlAs superlattice allowed the conversion of pump to third-harmonic radiation at 300 GHz with an efficiency of about 1% (power∼30 μW).