加偏置电场的双曲线量子阱中线性与三阶非线性光学吸收系数的计算(英文)

Calculation of Linear and Nonlinear Intersubband Optical Absorption in Electric-field Biased Hyperbolic Quantum Wells

利用紧致密度矩阵近似方法,研究了加偏置电场双曲线量子阱中的线性与三阶非线性光学吸收系数.得到了该系统中的线性与三阶非线性光学吸收系数的解析表达式.分析了势阱的形状、外加电场的大小以及入射光场的强度对吸收系数的影响规律.文章以典型的AlxGa1-xAs/GaAs双曲线量子阱为例作了数值计算.结果表明:随着势阱宽度的增加,系统的吸收系数将减小;随着外加电场的增加,系统的非对称性增加,系统的吸收系数将增加;随着外加光场强度的增加,系统的吸收系数将减小,并且当光强增加到一定值时会出现明显的饱和吸收现象,这一结论为进一步的实验研究提供了相应的理论依据.

The analytic forms of the linear and the third-order nonlinear optical intersubband absorption coefficients were obtained for general asymmetric quantum well systems using the density matrix formalism. Based on the model, the linear and the third-order nonlinear intersubband optical absorptions in electric-field biased hyperbolic quantum wells were studied. The numerical results were presented for a typical AlxGa1-x As/ GaAs electric-field biased hyperbolic quantum wells. The results show that the contributors to the nonlinear absorption coefficient are due to the electric field, the shape of quantum well and the optical intensity.