Understanding and selecting diffraction gratings

Diffraction gratings are used in a variety of applications where light needs to be spectrally split, including engineering, communications, chemistry, physics, and life sciences research.

Understanding the varying types of gratings will allow you to select the best option for your needs. Diffraction gratings are passive optical components that produce an angular split of an incident light source as a function of wavelength. Each wavelength exits the device at a different angle, allowing spectral selection for a wide range of applications.

Typically, a grating consists of a series of parallel grooves, equally spaced and formed in a reflective coating deposited onto a suitable substrate. The distance between each groove and the angles the grooves form in respect to the substrate influence both the dispersion and efficiency of a grating. If the wavelength of the incident radiation is much larger than the groove spacing, diffraction will not occur. If the wavelength is much smaller than the groove spacing, the facets of the groove will act as mirrors and, again, no diffraction will take place.