Distributed feedback laser with varying electrical resistance for uniform gain inside the optical waveguide

摘要

An electrooptic device ( 1 ) such as a distributed feed back semiconductor laser or a semiconductor modulator comprises an optical waveguide. A contact layer ( 11 ) is applied to the optical waveguide for conducting electrical current to the device for driving or modulating it. The contact layer is connected to the end of an electrically conducting path ( 3 ) and can have a shape, as seen perpendicularly to the surface of the device, to give an electric resistance between the end of the path and different areas at the optical waveguide which resistance is higher for areas located close to the ends of the device than for areas are located at the central region of the device. The shape can be si-milar to a trapezium having concave oblique sides and is selected so that the resulting varying electrical resistance gives a sub-stantially uniform electrical power or gain inside the optical waveguide, taken in the longitudinal direction of the waveguide.