Ap-i-nresonant tunnel diode is designed and investigated using photoluminescence (PL) spectroscopy. The device is based on anAl0.4Ga0.6As/GaAsgraded-index waveguide heterostructure enhanced by aperiodic-superlattice injectors for simultaneous resonant injection of electrons and heavy holes. The bias-dependent study of photocurrent, electroluminescence (EL) and PL show strong resonance behavior in the optical intensity confirming the field-dependent resonant injection of the excited states in the emission layers. Pronounced voltage-current bistability due to injection efficiency leads to multiple-wavelength EL and lasing action. ©1998 American Institute of Physics.