Information exchange in free space using spectral switching of diffracted polychromatic light: possibilities and...

Spectral switching is now a well-known phenomenon. Several research groups have studied it theoretically and experimentally for different optical systems. Recently, its potential applications have been demonstrated for information encoding and transmission in free space. In this paper we report experimental observations in the far field for spectral switching of polychromatic light passing through an astigmatic aperture lens. An information encoding scheme, a free-space optical link, and related boundary conditions are studied in detail. In addition, on the basis of experimental and theoretical studies carried out so far for spectral switching, we explore possibilities of information transmission in free space and analyze experimental limitations of spectral-switching-based free-space optical communication.