| 摘要 |
PROBLEM TO BE SOLVED: To provide a wavelength selective switch capable of suppressing a cross talk between modes in a wavelength region of the channel boundary of a deflection element and narrowing in a transmission band by discretely forming the wavelength dispersion of a wavelength dispersion element in a WSS and having a wide transmission band.SOLUTION: An input/output port group 101, a micro lens array 102, a wavelength dispersion element 103 having the direction of wavelength dispersion opposite to that of a diffraction grating 104 described later and having a FSR shorter than that of the diffraction grating 104, the diffraction grating 104, a lens 105 for condensing emission light from the diffraction grating 104 and a MEMS mirror array 106 are arranged in this order. Light entered into the wavelength dispersion element 103 is subjected to periodical diffraction with the period of FSR of the wavelength dispersion element 103 and is incident on the diffraction grating 104, and then wavelength dispersion in the diffraction grating 104 is periodically canceled by a periodical variation of a diffraction angle to a wavelength in the wavelength dispersion element 103. A condensing position on the deflection element array 106 is discretely changed to the wavelength by condensing the light with the lens 105.SELECTED DRAWING: Figure 1 |
