OPTICAL MODULATORS USING QUANTUM-CONFINED STARK-EFFECT IN ZNSE BASED MULTIPLE-QUANTUM-WELL STRUCTURES

Optical modulator structures employing quantum confined Stark effect tuning in ZnSe based material systems are described. Computations are presented to illustrate the feasibility of designing transmission and reflection mode Fabry-Perot modulators using ZnCdSe-ZnSSe (or ZnCdSe-ZnMgSSe) MQW cavities. Changes in the excitonic absorption coefficient (e.g., 3-5 nm shift in peak) and index of refraction (approximately 2%), in the presence of an externally applied perpendicular electric field E(perpendicular-to) (10(4)-10(5) V/cm), are calculated and used to obtain variations in transmittance (contrast ratio). Both matched and asymmetric Fabry-Perot structures realized on ZnSe and GaAs substrates are discussed. In contrast to the AlGaAs-GaAs system, the excitonic binding energies in the ZnCdSe-ZnSSe system are found to be significantly higher. The variations in excitonic wavefunction \phi(ex)\2 are, therefore, significantly different. However, the contrast ratios are not as good as for the AlGaAs-GaAs system due to poor dielectric mirror reflectivities.