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Optical Properties of Energy-Dependent Effective Mass GaAs/GaxIn1?xAs and GaAs/AlxGa1?xAs Quantum Well Systems: A Shooting Method Study
摘要： In this paper, we study the effect of energy-dependent effective mass on optical properties of GaAs/GaxIn1?xAs and GaAs/AlxGa1?xAs quantum well systems through the compact density matrix approach. We solved the resulting non-linear Schro¨dinger equation by a simple shooting method and present the algorithm. We show that the energy-dependent effective mass effect is more important for systems with narrower quantum well systems. By an energy-dependent effective mass assumption, absorption coef?cient peak height increases with increasing the total system length L while in the constant effective mass limit, absorption coef?cient peak heights have not been in?uenced by changing L. In the GaAs/AlxGa1?xAs system, by increasing the number of wells, the linear absorption coef?cient amplitude at ?rst increases and then decreases in the ?xed effective mass approximation and monotonically decreases in the energy-dependent effective mass case. By increasing the number of wells, the linear absorption coef?cient peak position at ?rst shows a blue shift and then shows a redshift. In the GaAs/GaxIn1?xAs system, the situation is more complicated and it is described in more detail in the text. However, GaAs/GaxIn1?xAs quantum well systems have larger values of absorption coef?cient peak heights than GaAs/AlxGa1?xAs ones.
关键词： shooting method,GaAs/GaxIn1?xAs and GaAs/AlxGa1?xAs Quantum wells,refractive index changes,energy-dependent effective mass,absorption coef?cient
更新于2025-09-23 15:21:21
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Optical characteristics of the undamaged and laser damaged K9 glass in terahertz band
摘要： K9 glass is an important optical element of the high energy laser system. In an attempt to investigate the variation of optical properties of K9 glass before and after laser induced damage, based on the transmission terahertz time-domain spectral system, the undamaged and the damaged K9 glasses induced by laser were tested to obtain the terahertz time-domain and frequency-domain spectra and the refractive index and absorption coef?cient of the samples were calculated in terahertz band for further analysis. Results show that with the increase of laser energy, from the undamaged to the damaged K9 glasses to different extent, the peak to peak value in time domain and the amplitude value in frequency domain present a decreasing trend in varying degrees, and in the 0.4～0.5 THz band, the absorption coef?cient increases continuously with a slight change of refractive index, which indicates that K9 glass not only appears the melting and fracture in the macroscopic morphology after laser-induced damage, but also forms non-bridged oxygen atoms in its microstructure with more ion bonds and free electrons and the change of ion polarization. In this regard, this paper provides a technical basis for exploring the micro characteristics of K9 glass after laser-induced damage, and lays a good foundation for the application of terahertz time-domain spectroscopy to laser-induced damage analysis.
关键词： terahertz time-domain spectrum,K9 glass,laser-induced damage,refractive index,absorption coef?cient
更新于2025-09-23 15:21:01