The use of flat diffractive optical elements (DOEs) for broadband applications, e.g. conventional optical systems, requires DOEs that maintain high efficiencies across the required range of wavelengths, angles of incidence, and grating periods. Here we introduce a general framework for how dispersion engineering can be used to design DOEs that fulfill these requirements and use our approach to determine design rules for broadband DOEs. Our analysis shows that the key to making échelette-type gratings (EGs) suitable for broadband optical systems is the development of new optical materials with specific uncommon dispersion properties. Subsequently, we use our framework to design a representative range of prototype EGs, which allows us to link the specifications of an optical system to the requirements on the EGs’ materials. Finally, we show that our design rules apply to all DOEs based on propagation delays including GRIN DOEs and metagratings. Our design rules therefore guide the way towards unlocking the full potential of DOEs for different kinds of broadband applications.

中文翻译：

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宽带应用中高效平板光学的一般设计形式

在宽带应用（例如常规光学系统）中使用平面衍射光学元件（DOE）要求DOE在所需的波长范围，入射角和光栅周期内保持高效率。在这里，我们介绍了一个通用框架，说明如何使用色散工程来设计满足这些要求的DOE，并使用我们的方法来确定宽带DOE的设计规则。我们的分析表明，制造适用于宽带光学系统的埃歇莱特型光栅（EGs）的关键是开发具有特殊不常见色散特性的新型光学材料。随后，我们使用我们的框架来设计代表性的EG原型系列，这使我们能够将光学系统的规范与EG的材料要求联系起来。最后，我们证明我们的设计规则基于传播延迟（包括GRIN DOE和元迁移）适用于所有DOE。因此，我们的设计规则指导了为各种宽带应用释放DOE的全部潜力的方法。