Superlattice surface-normal asymmetric Fabry-Perot reflection modulators: optical modulation and switching

The surface-normal asymmetric Fabry-Perot reflection modulators discussed are based on the electroabsorption stemming from the effective absorption edge blue shift caused by Wannier-Stark localization in superlattices. Due to the modulator's normally off characteristics at the Fabry-Perot resonance, they exhibit negative differential photoconductivity. When the modulator is connected to a similar modulator or a simple photodiode, the negative differential photoconductance at resonance enables the modulator to operate as a self-electrooptic effect device (SEED) that shows clear bistable loops, and also has very large on-off ratios at its output. The operating principle of these modulators and SEEDs, and their sensitivity to variations of operating wavelengths, layer thickness and composition, and temperature are discussed.<>