Operation and theoretical analysis of the multiple asymmetric coupled quantum-well light modulator in the n-i-n configuration

Results of optical measurements on a multiple asymmetric quantum-well device in the n-i-n configuration that demonstrate for the first time its applicability as a light modulator are presented. The contrast ratio at the fundamental heavy hole exciton resonance is close to 2 for small operating voltage of around 3.5 V. Dual wavelength operation was proved possible with a weaker contrast ratio at 1.68 eV. The energy levels and the absorption coefficient are calculated in the envelope function approximation within the eight-band k x p model with electric field-dependent transition energies in agreement with theory. Weak deviations from the step-like character of the calculated absorption spectrum are explained by the wave vector dependence of the optical matrix element.