Analysis of the attenuation ratio of MQW optical intensitymodulator for 1.55 μm wavelength taking account of electron wavefunction leakage

A theoretical analysis of an attenuation ratio for MQW optical intensity modulator was carried out taking account of the leakage of electron envelope function from the well layer. In the MQW modulator using InGaAsP material, the leakage of electron envelope function is large even for a low applied field because of the comparatively low potential barrier for electron. A normalization scheme in energy space was introduced for such leaky envelope function and field dependence of the Stark shift and oscillator strength have been analyzed by solving exciton effective mass equation. This approach was applied to MQW modulator for the wavelength of 1.55 μm for optical communication system. The well width and well number for large attenuation ratio with small residual absorption have been obtained. The calculation was compared with the experimental result and the difference was discussed