Variable optical damping element for e.g. planar fiber-optic cable, has decoupling waveguides arranged in output region of multi-mode interference coupler, where waveguides have taper with linear, elliptical or exponential characteristic

摘要

The element has a multi-mode interference coupler (MMI) including an input coupler with a taper (T2), arranged around a waveguide (W1), where the coupler exhibits a material e.g. polymer, with a variable refractive index. Two decoupling waveguides (W2) are provided for decoupling light and are arranged in an output region (AE) of the interference coupler. The decoupling waveguides have a taper (T3) with a linear, elliptical or exponential characteristic. The taper of the input coupler with reduced cross-section is connected to an output of the waveguide.