Abstract: A method for manufacturing branching-off or intersecting channel-shaped waveguides on or in a substrate, which substrate encloses a light-guiding layer, and on which substrate there is applied an auxiliary-mask layer having a thickness t, the method comprising steps of:applying a first mask pattern of a first mask material in a first mask position on the auxiliary-mask layer, the first mask pattern including a subpattern for defining a first channel-shaped waveguide;etching portions of the auxiliary-mask layer not covered by the first mask pattern using first etchants, the auxiliary-mask material being etched over a first etching depth d which is less than the thickness t;removing the first mask material of the first mask pattern;applying a second mask pattern of a second mask material in a second mask position which overlaps the position of the auxiliary-mask pattern at least in part, the second mask pattern including a subpattern for defining a second channel-shaped waveguide which makes an acute angle with

Abstract: Integrated optical mode converter provided with a channel-shaped waveguide comprising a periodic concatenation of two wave-guiding subsections (P) and (Q) defined by a strip-shaped structure supported by a substrate. The waveguide profiles of the subsections (P) and (Q) are defined by two different partial strips, of which at least one is, but preferably both are, provided with a slot (S.sub.P, S.sub.Q) running in a longitudinal direction of the partial strip in question. The slots have been applied in such a manner that only the field distribution of one of the two guided modes involved in the mode conversion is affected. The resulting structure has increased conversion per interface; and lower attenuation in specific embodiments.