Photonic switching by tunnelling-assisted absorption modulation in a GaAs sawtooth structure

The authors 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 Δλ>100 nm. A contrast ratio of 1:1.7 of the opaque and transparent states is obtained. Low-voltage operation (ΔV<5 V) and potential high-speed capability make the new device an attractive candidate for future photoionic switching systems