A semiconductor stripe laser has a first semiconductor region having a first conductivity type and a second semiconductor region having a different, second conductivity type. An active zone for generating laser radiation is located between the semiconductor regions. A stripe waveguide is formed in the second semiconductor region and is arranged to guide waves in a one-dimensional manner and is arranged for a current density of at least 0.5 kA/cm2. A second electrical contact is located on the second semiconductor region and on an electrical contact structure for external electrical contacting. An electrical passivation layer is provided in certain places on the stripe waveguide. A thermal insulation apparatus is located between the second electrical contact and the active zone and/or on the stripe waveguide.