Enhanced Second-Order Nonlinear Susceptibility in Type-II Asymmetric Quantum Well Structures

Zhang, Yong-Hang

Enhanced Second-Order Nonlinear Susceptibility in Type-II Asymmetric Quantum Well Structures

Posted on 2024-05-15 - 11:55

Asymmetric quantum wells (AQWs) utilizing interband transitions enhance second-order susceptibility over a wide wavelength range compared to natural crystals. The nonlinear susceptibility is further enhanced in AQWs with type-II band alignment as compared to type-I band alignment, a result of the larger interband charge shift. This enhancement is demonstrated in this work by analyzing three type-I and type-II AQW designs based on the lattice-matched InP/AlGaInAs materials systems using the envelope wavefunction approximation. The calculated interband second-order susceptibility tensor elements in type-II structures range between 20 pm/V to 1.60×10³ pm/V for nearly-resonant optical rectification and difference frequency generation applications at near-infrared and terahertz wavelengths, an improvement of nearly one order of magnitude over the type-I structures and 1-2 orders of magnitude over natural crystals such as LiNbO₃, KTiOPO₄ (KTP), or GaAs. A factor of 2-3 further enhancement of the tensor elements is achieved by optimizing the well widths and band offsets of the type-II asymmetric quantum wells. The type-II structure can be implemented in other materials systems spanning the longwave infrared to visible wavelengths, enhancing nonlinear susceptibility for various applications, including photonic integrated circuits.

CITE THIS COLLECTION

Qi, Xin; Khurgin, Jacob; Ju, Zheng; Schaefer, Stephen; Liu, Xiaoyang; Zhang, Yong-Hang (2024). Enhanced Second-Order Nonlinear Susceptibility in Type-II Asymmetric Quantum Well Structures. AIP Publishing. Collection. https://doi.org/10.60893/figshare.jap.c.7217310.v1

https://doi.org/10.60893/figshare.jap.c.7217310.v1

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