Diffraction efficiency is a measure of how effectively a diffractive optical element (DOE) or diffraction grating directs light into specific diffraction orders or achieves a desired optical effect. It is expressed as the ratio of the power or intensity of diffracted light in a particular order to the total incident power or intensity.
In a diffraction grating or DOE, when light interacts with the periodic structure (such as grooves or zones), it undergoes diffraction, resulting in the formation of diffracted orders. Each diffraction order corresponds to a specific angle and wavelength. Diffraction efficiency quantifies the effectiveness of the device in directing light into these orders.
Efficient diffraction gratings or DOEs are designed to maximize the diffraction efficiency in desired orders while minimizing losses in unwanted orders or through other optical effects like absorption or scattering. Achieving high diffraction efficiency is crucial in various applications, including spectroscopy, telecommunications, laser systems, and other optical devices where precise control over light distribution is essential.