Space–bandwidth product of optical signals and systems

TLDR

The space–bandwidth product (SW) is a fundamental metric for assessing optical system performance, traditionally defined as a pure number counting the system’s degrees of freedom. The authors propose that a quasi‑geometrical representation of the SW in the Wigner domain is more useful. They represent the input signal as a SW in the Wigner domain. Perfect signal processing requires the system’s SW to fully encompass the signal’s SW.

Abstract

The space–bandwidth product (SW) is fundamental for judging the performance of an optical system. Often the SW of a system is defined only as a pure number that counts the degrees of freedom of the system. We claim that a quasi-geometrical representation of the SW in the Wigner domain is more useful. We also represent the input signal as a SW in the Wigner domain. For perfect signal processing it is necessary that the system SW fully embrace the signal SW.