# Multilevel blazed diffraction gratings

Diffractive gratings are structures that have a periodic pattern of alternating transparent and opaque regions that can manipulate light waves. When a beam of light is incident upon a diffractive grating, the light is diffracted into multiple directions, creating a characteristic pattern of bright and dark regions. These gratings have found applications in a wide range of fields, including telecommunications, spectroscopy, and imaging. Unlike traditional reflective or refractive optics, diffractive gratings rely on interference effects to shape and direct light, offering unique advantages such as high efficiency, compact size, and ease of fabrication. In this way, diffractive gratings have become an essential tool in modern optics and photonics, allowing for precise control of light waves and enabling new technologies and applications.

In this example, we compute the grating efficiency of a multilevel diffraction grating whose design is inspired by the work of Oliva et al. (2011) (opens new window).

Tidy3D uses a near field to far field transformation specialized to periodic structures to compute the grating efficiency, and its accuracy is verified through a comparison with the semi-analytical rigorous coupled wave analysis (RCWA) approach, using the open-source library grcwa (opens new window).

To view the full example in Python, please click here (opens new window).