Injection laser manufacture

Claim 1

In a method of producing an inverted rib waveguide laser including an InP substrate having a (100) surface and an (In,Ga)(As,P) active layer, the improvement comprising the steps of forming at the (100) surface of the substrate a channel extending in the [011] direction by an etching process producing side walls of the channel that differ from A-planes; epitaxially growing an intermediate layer of an (In,Ga)(As,P) material with a band gap larger than that of the active layer by liquid phase epitaxy in the channel and on the (100) surface of the substrate to thereby form a rib filling the channel and providing a measure of dielectric waveguiding effect for the laser in the lateral directions, with the growth within and at the region substantially juxtaposed with the channel being accelerated relative to that on the (100) surface of the substrate due to the crystallographic orientations of the side walls so that that surface of the intermediate layer that is remote from and faces away from the substrate becomes substantially flat even when the thickness of the intermediate layer outside said region is still relatively small; and providing the active layer on the substantially flat remote surface of the intermediate layer by liquid phase epitaxy.