Combined local and carrier transport optical nonlinearities in a hetero n-i-p-i structure

Abstract
Nonlinear optical effects have been measured in a novel hetero nipi structure with strained InAs/GaAs superlattices as the quantum wells. For intensities below 6 W/cm2, changes in transmission are observed due to the screening of built‐in fields in conjunction with the quantum‐confined Stark effect. For intensities greater than 30 W/cm2, a further increase in transmission is observed due to state filling and exciton screening in the wells. It is demonstrated that a nipi structure, because of its lengthened carrier lifetime, can be used to reduce the intensity necessary for exciton saturation and state filling in quantum wells when the wells are placed in the i regions. Total changes in transmission greater than 25% have been seen, with no sign that the nonlinearity is saturating at 1 kW/cm2 (the highest excitation used here).