Asymmetric Fabry–Perot reflection modulators using red- and blue-shifted electroabsorption effects

Applying electric fields along the quantum-confined direction of superlattices generates either red-shift (quantum-confined Stark effect) or blue-shift (field-induced Stark localization in superlattices) electroabsorption effects, and the dominating effect changes from a blue-shift to a red-shift as the superlattice period increases from small values. Both effects are utilized in asymmetric Fabry–Perot structures to implement high-contrast electro-optic modulators. In comparison, the red shift provides lower insertion loss while the blue shift provides lower operating voltage swings.