Diode laser, comprising: a first contact having a first lateral width for injection of charge carriers; a first cladding layer, wherein the first contact contacts the first cladding layer; a first waveguide layer arranged on the first cladding layer; an active layer suitable for generating radiation, which is arranged on the first waveguide layer; a second waveguide layer disposed on the active layer; a second cladding layer disposed on the second waveguide layer; and a second contact having a second lateral width for injection of charge carriers, the second contact contacting the second cladding layer; wherein the first cladding layer, the first waveguide layer, the active layer, the second waveguide layer, and the second cladding layer are formed as a layer stack extending in the longitudinal direction between an exit facet and a reflection facet; wherein the active layer, the first contact and the second contact each extend at least partially between the exit facet and the reflection facet; and wherein the region commonly enclosed between the contacts (22, 24) by perpendicular projection of the second contact onto the first contact when projected in the vertical direction forms a current-carrying active region; wherein the active layer, the first contact and the second contact each have a lateral width greater than 10 μm, the current-carrying region in the region of the active layer has a width greater than 10 μm, and an anti-waveguide layer is arranged outside the active region in the layer stack, wherein the anti-waveguide layer is designed for resonant decoupling of lateral modes of higher order from the active region, wherein the refractive index of the anti-waveguide layer is greater than the minimum refractive index of the cladding layers (14, 22), and wherein a minimum lateral distance (d x) between the anti-waveguide layer and a projection of one of the contacts (22, 24) into the plane of the anti-waveguide layer is between 0 and 100 μm; characterised in that a vertical thickness (d) of the anti-waveguide layer and the refractive index n of the anti-waveguide layer satisfies condition: 0 ≤ n1 eff − n2 eff < 0.15 where n1 eff is the effective refractive index in the active region and n2 eff is the effective refractive index in the region of the anti-waveguide layer. a first contact having a first lateral width for injection of charge carriers; a first cladding layer, wherein the first contact contacts the first cladding layer; a first waveguide layer arranged on the first cladding layer; an active layer suitable for generating radiation, which is arranged on the first waveguide layer; a second waveguide layer disposed on the active layer; a second cladding layer disposed on the second waveguide layer; and a second contact having a second lateral width for injection of charge carriers, the second contact contacting the second cladding layer; wherein the first cladding layer, the first waveguide layer, the active layer, the second waveguide layer, and the second cladding layer are formed as a layer stack extending in the longitudinal direction between an exit facet and a reflection facet; wherein the active layer, the first contact and the second contact each extend at least partially between the exit facet and the reflection facet; and wherein the region commonly enclosed between the contacts (22, 24) by perpendicular projection of the second contact onto the first contact when projected in the vertical direction forms a current-carrying active region; wherein the active layer, the first contact and the second contact each have a lateral width greater than 10 μm, the current-carrying region in the region of the active layer has a width greater than 10 μm, and an anti-waveguide layer is arranged outside the active region in the layer stack, wherein the anti-waveguide layer is designed for resonant decoupling of lateral modes of higher order from the active region, wherein the refractive index of the anti-waveguide layer is greater than the minimum refractive index of the cladding layers (14, 22), and wherein a minimum lateral distance (d x) between the anti-waveguide layer and a projection of one of the contacts (22, 24) into the plane of the anti-waveguide layer is between 0 and 100 μm; characterised in that a vertical thickness (d) of the anti-waveguide layer and the refractive index n of the anti-waveguide layer satisfies condition: 0 ≤ n1 eff − n2 eff < 0.15 where n1 eff is the effective refractive index in the active region and n2 eff is the effective refractive index in the region of the anti-waveguide layer.