Frequency conversion using nonlinear optical (NLO) crystals is widely used in advanced photonic technologies to produce coherent light in the spectral regions where the available laser sources are missing. Isotropic glasses usually do not show second order nonlinear processes like second harmonic or difference frequency generation (SHG, DFG) except for temporarily induced anisotropy under external stimuli. Here, we show that a HgI₂–Ga₂S₃–GeS₂ homogeneous glass exhibits a strong intrinsic SHG response comparable with that of the well‐known NLO single crystal LiNbO₃. The origin of this extremely rare phenomenon seems to be noncentrosymmetric bent HgI₂ molecules embedded in a sulfide glassy host. Taking into account the unique properties of chalcogenide glasses (wide IR transmission, low phonon density, unlimited ability to be modified changing the appropriate glass properties, fiber drawing and thin layer design), the observed phenomenon opens up the possibility of creating fundamentally new devices for mid‐IR photonics.

中文翻译：

---

含HgI2的硫族化物玻璃的本征二阶非线性

使用非线性光学（NLO）晶体的频率转换已广泛用于先进的光子技术中，以在缺少可用激光源的光谱区域中产生相干光。各向同性眼镜通常不显示诸如二次谐波或差频生成（SHG，DFG）之类的二阶非线性过程，只是在外部刺激下会暂时引起各向异性。在这里，我们证明了HgI ₂ -Ga ₂ S ₃ -GeS ₂均质玻璃具有与众所周知的NLO单晶LiNbO ₃相当的强大的固有SHG响应。这种极为罕见的现象的起源似乎是非中心对称弯曲的HgI ₂嵌入硫化物玻璃状主体中的分子。考虑到硫族化物玻璃的独特性能（宽红外透射率，低声子密度，无限制的修改适当的玻璃性能，纤维拉伸和薄层设计的能力），所观察到的现象为建立用于制造新型器件的可能性提供了可能性。中红外光子学