Patent ID: 8437634

Claim:
A wavelength selective optical switch device comprising: an entrance/exit section which receives a WDM signal light beam composed of multi-wavelength light, and allows exit of optical signal of selected wavelengths; a wavelength dispersion element which spatially disperses the WDM signal light beam according to their wavelengths and multiplexing reflected light beams; a light condensing element which condenses light beams dispersed by said wavelength dispersion element; a wavelength selective element which has a plurality of pixels that are placed on positions to receive incident light developed over an xy plane composed of an x-axis direction developed according to wavelength and a y-axis direction perpendicular to the x-axis direction, and arranged in a lattice pattern on the xy plane, the wavelength selective element being used as a multi-level optical phased array to periodically change a phase shift characteristic of each two-dimensional pixel; and a wavelength selective element driving unit which drives each of the pixels arranged in the x-y directions of said wavelength selective element to change the phase shift characteristic according to wavelength and reflects light beams in different directions according to their wavelengths, wherein a maximum phase shift amount of said optical phased array is set at least 1.5π and less than 2.0 π.