Abstract
Superpositions of coherent light waves typically interfere. We present superpositions of up to six plane waves which defy this expectation by having a perfectly homogeneous mean square of the electric field. For many applications in optics these superpositions can be seen as having a homogeneous intensity. Our superpositions show interesting one- two- and three dimensional patterns in their helicity densities, including several that support bright regions of superchirality. Our superpositions might be used to write chiral patterns in certain materials and, conversely, such materials might be used as the basis of an 'optical helicity' camera capable of recording spatial variations in helicity.
Highlights
The electric and magnetic fields of a plane electromagnetic wave are orthogonal to each other and the direction of propagation
If one is content with only the mean square of the electric field being homogeneous without requiring that the mean square of the magnetic field be homogeneous, larger superpositions are allowed
The same reasoning applies for more than two pairs of interfering waves with the same wavevector difference. It is this trick that allows us to superpose more than three plane waves while keeping the mean square of the electric field homogeneous
Summary
The electric and magnetic fields of a plane electromagnetic wave are orthogonal to each other and the direction of propagation This suggests that the maximum number of waves with the same frequency that can be superposed without any interference is three. The helicity density, a quantity that indicates the handedness of the light [1,2,3,4,5], is in general inhomogeneous for our noninterfering superpositions. It will vary in space in a pattern that is quite often, not necessarily, periodic and resembles the intensity variations in optical lattices.
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