A high-power 880-nm diode-directly-pumped passively mode-locked $1342\mathrm{nm}$ $\mathrm{Nd}\text{:}{\mathrm{YVO}}_4$ laser was demonstrated with a semiconductor saturable absorber mirror (SESAM). The laser mode radii in the laser crystal and on the SESAM were optimized carefully using the ABCD matrix formalism. An average output power of $2.3\mathrm{W}$ was obtained with a repetition rate of $76\mathrm{MHz}$ and a pulse width of $29.2\mathrm{ps}$ under an absorbed pump power of $12.1\mathrm{W}$ , corresponding to an optical-optical efficiency of 19.0% and a slope efficiency of 23.9%, respectively.