We have measured the characteristics of SiGe-Si quantum-web (QW) waveg
uide electroabsorption modulators grown by molecular beam epitaxy (MBE
). The modulation is based on the decoupling of the electron wavefunct
ion from the shallow wells for electrons with a small band-bending. A
100-mu m-long modulator demonstrates contrast ratio and insertion loss
of 1.43 and 28.5 dB, respectively.