Normally-off high-contrast asymmetric Fabry–Perot reflection modulator using Wannier–Stark localization in a superlattice

Abstract

A normally-off surface normal Fabry–Perot reflection modulator with a contrast ratio of more than 60:1 with an operating voltage swing of 8 V has been demonstrated. The asymmetric Fabry–Perot structure consists of 100 periods of a 30 Å GaAs/30 Å Al0.3Ga0.7As superlattice sandwiched between a highly reflecting quarter-wavelength stack on the substrate side, and a less reflecting front mirror (air-semiconductor interface) on the top. The net Fabry–Perot reflection is turned on by reducing the cavity loss at resonance through the blue-shifted electroabsorption effect of Wannier–Stark localization in the superlattice.