SEMICONDUCTOR WAVEGUIDE TYPE POLARIZED WAVE ROTATING ELEMENT

摘要

PROBLEM TO BE SOLVED: To increase the rotational efficiency of a polarized wave in a semiconductor waveguide type polarized wave rotating element utilizing a curved waveguide. SOLUTION: The semiconductor waveguide type polarized wave rotating element capable of rotating the polarization plane of light is constituted of mutually connecting a pair of linear waveguides by plural curved waveguide segments connected in series. In the cross-sectional structure of the rotating element, a rib sidewall angle 28 is inclined from a substrate 23 at an angle other than right angle. A guide layer 21 has an under etched layer 27 on the substrate 23 side. When the angle 28 and the thickness of the layer 27 are set up to respective optimum values as parameters, a polarized wave rotating characteristic can be improved.