Optical detection of resonant tunneling of electrons in quantum wells.

Clear evidence for resonant tunneling of electrons in a p-i- n quantum well modulator is provided by picosecond pump-and- probe electroabsorption measurements. The temperature independent escape times show a drastic reduction when an electrical field is applied perpendicular to the wells, with a pronounced minimum at the field corresponding to the resonance between the n=1 electron level in one quantum well, and the n=2 electron level in the adjacent one. Our calculated field dependence of the electron tunneling times proves that this behavior is the signature of resonant tunneling.