OPTISCHER WELLENLEITER-SCHALTER MIT EINEN RICHTKOPPLER BILDENDEN STREIFEN-WELLENLEITERN, DER DURCH INJEKTION VON LADUNGSTRAEGERN GESCHALTET WIRD.

摘要

The coupler contains 2 parallel strip-guides (3,4) and a pn-junction allowing injection of charge carriers. The guides are separated by a gap (a) of which the refractive index is modified by the charge injection. On an n-InP substrate (1) p-type diffusions are formed (12) which extend to the inner edges of the guides (3,4) or even further. The strip guides (3,4) are formed by first etching the substrate and subsequently depositing epitaxially a layer of InGaAsP (7) with a lattice constant adapted to the host-crystal. A further area (10) may also be formed in this way. This layer is then coated with a mantle-layer (6) of InP, which is followed by a contact layer (8). A p-type diffusion is formed int he mantle witha width which extends to the inner edges of the strip-guides (3,4) and in the other direction runs parallel with the guides (11). A mask of SiO2 (9) is applied to the contact layer (8) to restrict the size of the contact area. A voltage is applied between the contacts 5 and 2 to cause injection via the pn-junction at the edge of the area (11). A strip (10) formed between the 2 guides (3,4) may also be used as an additional wave-guide.