Various electro-optical modulator module designs are presented, which can provide for uniform, symmetric, and efficient heat removal for mode-locking, Q-switching, and/or cavity dumping operations. Heat can be uniformly extracted from an EO crystal without imposing undue stress, thereby preventing birefringence and laser beam degradation. A liquid-cooling approach can be used for high-duty operations, such as mode-locking operations. Efficient heat removal can prevent thermal run-away from electrical heating of the crystal due to the large drop in the electrical resistance of CdTe with increasing temperature when operated above 50.degree. C. RF or video arcing and subsequent damage to the EO crystal can be prevented by surrounding the crystal with a low dielectric constant material that lowers the capacitance coupling to ground, while still maintaining good thermal cooling.