OPTICAL ELEMENT AND OPTICAL INFORMATION PROCESSOR USING THE ELEMENT AND PRODUCTION OF OPTICAL ELEMENT

摘要

PURPOSE:To provide the polarization separating element which can be produced by the simple process for production without requiring mask alignment and has high reliability, good productivity and good extinction ratio. CONSTITUTION:Proton exchange layers 21 are periodically formed on a lithium niobate substrate 20 of an x face and further, grooves 24 are formed by selective etching using hydrofluoric acid. The light transmitted through the proton exchange layers 21 and grooves 24 of the polarization separating element produced in such a manner generates a deviation in phases with the light which does not transmit these parts. A phase advance takes place in both the proton exchange layers 21 and the grooves 24 when ordinary light is made incident, but a phase delay takes place in the proton exchange layers 21 and the phase advance in the grooves 24, thus acting in the directions where the deviations in the phases are offset with each other if extraordinary light is made incident. The polarization separating element which diffracts the ordinary light and does not diffract the extraordinary light is obtd. by adequately selecting the depth of the proton exchange layers 21 and the grooves 24.