We reveal the potential of bound states in the continuum (BIC) to enhance the nonlinear response in specialty optical resonators in the presence of gain and loss. We demonstrate this phenomenon in a square core-shell AlGaAs nanowire having a proper engineered spatial variation of gain and loss to sustain quasi-BICs. The presence of these high-quality modes at both fundamental and second-harmonic wavelengths leads to an extremely high enhancement in second harmonic generation, thus preluding a framework to fabricate composite media with high effective nonlinearity.

中文翻译：

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连续状态中束缚态的增益损失工程，用于增强介电纳米腔中的非线性响应。

我们揭示了在存在增益和损耗的情况下，连续谱（BIC）中的束缚态潜力，可以增强特种光学谐振器中的非线性响应。我们在具有适当设计的增益和损耗空间变化以维持准BIC的方形核-壳AlGaAs纳米线中证明了这一现象。这些高质量模式在基波和二次谐波波长上的存在会导致二次谐波的产生极高的增强，从而为制造具有高效非线性的复合介质提供了框架。