NEW ALL-OPTICAL REFLECTION MODULATOR BASED ON A DOUBLY RESONANT HETERO-NIPI SATURABLE BRAGG REFLECTION

Very large fractional reflectivity changes (30%) under optical pump densities of almost-equal-to 3 mW/cm2 are found in a novel GaAs/Al0.35Ga0.65As hetero-nipi structure grown by MBE. This high sensitivity originates in the interaction between the n = 1 heavy-hole excitonic resonances in the hetero-nipi and an optical Bragg resonance, designed into the structure through its optical periodicity. The dynamics of the nonlinearity are shown to be dominated by the "giant ambipolar diffusion" mechanism for in-plane carrier transport, and the implications of this for device applications are discussed.