Large field-induced refractive index change without red shift of absorption edge in five-step asymmetric coupled quantum wells with modified potential

A structure composed of five-step asymmetric coupled quantum wells (FACQWs) is first proposed for large field-induced refractive index change without red shift of absorption edge. A strong exciton absorption peak is caused by e1hh2 and e2hh1 transitions with a small applied electric field. The field-induced refractive index change of FACQWs is larger by one order compared to that of rectangular quantum well when the operation wavelength is apart from absorption edge.