Optical Nonlinearity Caused by Charge-Induced Field Screening in DC-Biased Quantum Well Structures

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Abstract
The optical nonlinear properties caused by charge-induced field screening are observed in dc-biased quantum well structures which are well designed to accumulate photo-excited carriers. The field-induced shift in the peak energy of the exciton absorption is systematically reduced with increasing intensity of the incident light. The rapid change of the absorption coefficient at a low optical power level (∼1 W/cm2) occurs, demonstrating a positive feedback due to the charge polarization. The switching energy and response time are estimated to be 4.6 fJ/µm2 and 460 ns, respectively.