<title>Optical switching in diffraction of partially coherent light: spectral switching</title>

Abstract

ABSTRACTIn this paper a new kind optical switch, which is called spectral switch, is presented. When a particular class ofbroad-band partially coherent light is diffracted by a circular aperture, the spectrum of the light in the far zone of thediffractive field is different from the spectrum at the aperture, i.e., there exists spectral shift Aw = Wm W (COrn 1S thefrequency at which the spectrum of the diffractive field takes its maximum, and ii is the frequency at which thespectrum at the aperture takes its maximum). It is demonstrated that when the spectral coherence of the light at theaperture changes, there will be gradual change in the spectral shift. However when the coherence is equal to a criticalvalue, the spectral shift will exhibit a rapid transition. We call this phenomenon as spectral switch. The scheme forgenerating lxN spectral switch is also discussed.Key words: optical switching, spectral switching, partially coherent light, diffraction. 1. INTRODUCTION op tical switches are important devices in optical interconnects and optical communications. Until now there have