The future project for Japanese gravitational wave detection, called the large-scale cryogenic gravitational wave telescope (LCGT), requires a high-power laser with good beam quality. Two side-pumped Nd:YAG rod lasers are being developed for multi-stage injection locking. The intermediate-stage laser produced an output power of 30 W in a linear laser cavity configuration and 17 W in a ring cavity configuration. The ring cavity was designed to compensate for thermal birefringence by rotating the polarization at the Nd:YAG rod. The final-stage laser is aiming for 100 W output power. An output power of 60 W was obtained for the prototype laser in a linear cavity configuration and 39 W in a ring cavity configuration. The laser module contained two Nd:YAG rods and a quartz rotator in order to compensate for thermal birefringence.