Optical switching in diffraction of partially coherent light: spectral switching

摘要

In this paper a new kind optical switch, which is called spectral switch, is presented. When a particular class of broad-band partially coherent light is diffracted by a circular aperture, the spectrum of the light in the far zone of the diffractive field is different from the spectrum at the aperture, I.e., there exists spectral shift Δω=ω_m - ω (ω_m is the frequency at which the spectrum of the diffractive field takes its maximum, and ω is the frequency at which the spectrum at the aperture takes its maximum). It is demonstrated that when the spectral coherence of the light at the aperture changes, there will be gradual change in the spectral shift. However when the coherence is equal to a critical value, the spectral shift will exhibit a rapid transition. We call this phenomenon as spectral switch. The scheme for generating 1XN spectral switch is also discussed.