Exciton effects on second-order nonlinear susceptibility in a quantum well with an applied electric field

The second-order nonlinear susceptibility in a quantum well with an applied electric field is calculated theoretically with the exciton effects taken into account. All transitions including bound-exciton to bound-exciton states, bound-exciton to continuum-exciton states, and continuum-exciton to continuum-exciton states are included. It is found that the bound- to bound-exciton contribution accounts for only about 25% of the total ‖d(2ω)‖. The major contribution is due to the continuum-state transitions.