PHOTONIC SWITCHING BY TUNNELLING-ASSISTED ABSORPTION MODULATION IN A GAAS SAWTOOTH STRUCTURE

We report on an electrically controlled optical modulator using a novel GaAs sawtooth structure. This structure consists of alternating n-type and p-type delta-doped GaAs. Modulation of tunnelling-assisted absorption is achieved by changing the internal electric field which in turn is controlled by external bias. Modulation of light intensity is demonstrated over a broad spectral range of DELTA lambda greater than 100 nm. A contrast ratio of 1:1 multiplied by (times) 7 of the opaque and transparent states is obtained. Low-voltage operation ( DELTA V greater than 5v) and potential high-speed capability make the new device an attractive candidate for future photonic switching systems.