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Maxwell2D: Grism

Dielectric constant distribution

A grism is a prism on which has been etched the grooves of a diffraction grating. It is used in astronomical instruments to filter light into different frequencies. In this example, two frequencies enter the prism from the base, and on leaving the other side, a significant fraction of the radiation is refracted in the direction that would be expected for a usual prism. However, there is an additional diffracted component, the angle of which is frequency dependent.
Wikipedia link: Grism

Electric field animation

Time-averaged Poynting vector

This is an animation of the component of the electric field out of the plane of the page.The direction in which energy is travelling at any instant is proportional to the cross product of the electric and magnetic fields, known as the Poynting vector. The arrows show the direction of the Poynting vector averaged over the simulation, while the colours show its strength.