We report on studying tunnel junctions and an optical cavity structure for developing epitaxially-stacked high-efficiency 905 nm high-power laser diodes. The GaAs tunnel junctions were explored via simulations and experiments to realize a high peak current density of 7.7 x 10(4) A/cm(2) and a low specific resistance of 1.5 x 10(-5) omega cm(2) with a high n-doping concentration of 6 x 10(19) cm(-3). Employing a low-loss epitaxial structure design, single-, double-, and triple-cavity structure laser diodes demonstrated power scaling by epitaxial stacking. Triple-cavity laser diodes have a low optical loss (0.42 cm(-1)) and generate a peak power of 83 W with a short cavity length of 750 mu m at a limited current of 30 A.