We present a compact and efficient KTA-based intracavity optical parametric oscillator (IOPO) driven by a diode-end-pumped $\mathrm{Nd}\text{:}{\mathrm{GdVO}}_4/\mathrm{Cr}\text{:}\mathrm{YAG}$ passively Q-switched laser. At the incident diode pump power of $9.2\mathrm{W}$ , signal ( $1.53\mathrm{\mu m}$ ) and idler ( $3.47\mathrm{\mu m}$ ) average output powers of up to 744 and $356\mathrm{mW}$ , respectively, have been obtained. The total ( $\text{signal}+\text{idler}$ ) optical-to-optical conversion efficiency is as high as 12%. By using the knife-edge method, near-diffraction-limited signal and idler beams have been detected, and the $M^2$ factors are well within 1.2. In addition, based on the ABCD matrix theory, the impact of mode matching and the thermal lens effect on the OPO output have been analyzed.