A monolithically integrated laser diode chip having a construction as a multiple beam laser diode, which, on a semiconductor substrate (3) comprised of GaAs, has at least two laser stacks (4a, 4b, 4c) which are arranged one above another and which each contain an active zone (7). The active zone (7) is in each case arranged between waveguide layers (8). The waveguide layers (8) each adjoin a cladding layer (6) at a side remote from the active zone. At least one of the waveguide layers (8) or cladding layers (6) of at least one laser stack (4a, 4b, 4c), comprises AlxGa1-xAs, where 0≦x≦1, and at least one additional material from main group III or V, such that the lattice mismatch between the at least one waveguide layer (8) or cladding layer (6) comprising the at least one additional element and the semiconductor substrate (3) composed of GaAs is reduced. This increases the lifetime of the laser diode chip.