Integrated strip type optical ribbed waveguide for high bit rate receiver

摘要

The waveguide (2) is formed on the surface (10) of a substrate together with an integrated photodiode (3) that is optically coupled to the waveguide (2). A flat layered waveguide (20) is formed on a buffer layer (11) of n+ doped InP arranged on or over the surface. A layer (21) of n- doped InP is arranged on the buffer layer and below a wave-guiding layer (22) of n- doped InGaAsP with a gap wavelength of 1.05 microns. A second waveguiding layer (23) with a gap wavelength of 1.3 microns is arranged on the first wave-guiding layer. A top layer (24) is arranged on the second wave-guiding layer and a layer island (300) is arranged on the top layer only partly covering the waveguide (20). The photodiode (3) is located in the island (300) with layers of n+ doped InP, n- doped InGaAs, n- doped InP and p+ doped InGaAs arranged on the top layer. The island has an edge (301) bounding the waveguide (2) and standing at an angle to the substrate surface and has at least one partial region which encloses the island and the top layer, and a partial region which does not have these layers and so reveals an n- doped layer of the island. A p+ doped region is provided in part of the island which defines a transition to the photodiode (3). p and n contacts of the diode are provided on p and n doped layers respectively. Outside the island, the waveguide is structured so it has a rib (240) of given width which runs along an axis parallel to the substrate surface and directed to the edge of the island. The rib is defined at the sides by an edge, the edges define regions of the waveguide where the wave-guiding layers are revealed. the rib and the waveguide at its edges define a strip-type ribbed waveguide (2).