Abstract: An index guided semiconductor laser possessing both index tailoring and gain tailoring is provided. Modern semiconductor lasers are fabricated utilizing a suitable material system (such as GaAs—AlGaAs or InP—InGaAsP) heterostructures are formed by crystal growth technologies such as MOCVD to create an active layer providing carrier and optical confinement, a lateral waveguide created by a ridge waveguide and a Fabry-Perot cavity formed from cleaved facets. The semiconductor lasers are configured in diode fashion with p-type and n-type regions between contacts creating current path. Lateral optical confinement is accomplished by a ridge type waveguide formed either by regrowth or etching techniques, designed to possess an index step and index width conducive to supporting two modes (hence index tailored). Lateral gain confinement confining the current density to a thin layer centered in the ridge waveguide.