A high-power electro-optic modulator (EOM) is formed to use specialized electrodes of a material selected to have a CTE that matches the CTE of the modulator's crystal. Providing CTE matching reduces the presence of stress-induced birefringence, which is known to cause unwanted modulation of the propagating optical signal. The specialized electrodes are preferably formed of a CuW metal matrix composite having a W/Cu ratio selected to create the matching CTE value. Advantageously, the CuW-based electrodes also exhibit a thermal conductivity about an order of magnitude greater than conventional electrode material (brass, Kovar) and thus provide additional thermal stability to the EOM's performance.