Totally kink-free and very-narrow-stripe proton-isolated injection lasers are presented. The standard gold-indium metal-contact bonding system has been investigated, and as a result an improved bonding technique is presented. Kink-free lasers with output power up to 20 mW have been accelerated at 80°C ambient for 1000 h without any change in thermal resistance and with an expected lifetime of above 106 h at room temperature.