Nitride-based blue laser diode structures with either Al0.83In0.17N/Al0.07Ga0.93N or Al0.87In0.13N bottom claddings have been fabricated and compared to standard structures including solely Al0.07Ga0.93N bottom claddings. Lasing emission at 415 nm is achieved in gain-guided structures at room temperature under pulsed current injection. Devices including the Al0.83In0.17N/Al0.07Ga0.93N bottom cladding exhibit superior device performance. This is a consequence of a better optical mode confinement, as expected from modeling.