Optical waveguide branching component with MMI couplers

摘要

An optical branching component particularly suitable for use as a tap device, has two optical waveguides 10, 12 coupled between two optical couplers 13,14 which each include at least one MMI 3,4 supporting at least two guided modes. There is an effective optical path length difference between the two waveguides and the coupling strength of at least one of the couplers monotonically decreases with increasing wavelength in the operational wavelength region of the component. This means a coupler with relatively large coupling strength and relatively low polarisation dependency can be used in the component, giving low polarisation dependent variation in the tap ratio, particularly for small tap ratios.