Lasing from GaAs Gunn devices

Abstract

Lasing from a GaAs Gunn device with a Fabry–Perot (F–P) cavity and a vertical-cavity structures are demonstrated. Light output-electric field characteristic of both F–P and vertical cavity structure Gunn device shows abrupt increase in light output above a negative differential resistance (NDR) threshold, implying cavity gain overcoming over loss. Electroluminescence (EL) spectra from the F–P Gunn device measured at 95 K show a significant spectral narrowing with increasing the applied voltage pulse width, indicative of monochromatic stimulated emission due to band-to-band recombination of impact-ionized carriers. The spectra from the vertical-cavity device are in accord with the cavity resonance as defined by the distributed Bragg reflectances (DBRs). The theoretical model on carrier generation via impact ionization inside the propagating space charge domains shows clearly that the built-up excess carrier density in the cavity indeed reaches the lasing threshold.