Electric field switching in a resonant tunneling diode electroabsorption modulator

The basic mechanism underlying electric field switching produced by a resonant tunnelling diode (RTD) is analysed and the theory compared with experimental results; agreement to within 12% is achieved. The electro-absorption modulator (EAM) device potential of this effect is explored in an optical waveguide configuration. It is shown that a RTD-EAM can provide significant absorption coefficient change, via the Franz-Keldysh effect, at appropriate optical communication wavelengths around 1550 nm and can achieve up to 28 dB optical modulation in a 200 um active length device. The advantage of the RTD-EAM, over the conventional reversed biased pn junction EAM, is that the RTD-EAM has in essence an integrated electronic amplifier and therefore requires considerably less switching power.