Optical element having wavelength selectivity

摘要

An optical element having wavelength selectivity, which is easy to manufacture and reduces the manufacturing cost. The optical element comprises a lens array (12) having one end face and a plurality of lenses (L1-L8) arranged on the one end face, and a multi-layered film filter (13) formed on the one end face (14) of the lens array. The multi-layered film filter includes high refractive-index dielectric layers and low refractive-index dielectric layers laminated alternately and its film thickness continuously changes in accordance with positions of the individual lenses. The center wavelength of transmitted light from the multi-layered film filter varies in accordance with the position of the lens array. In a case where mixed light enters the multi-layered film filter from the individual lenses, the mixed light is demultiplexed into lights of different center wavelengths by the multi-layered film filter that has difference thicknesses.