An attenuating counter-propagating (ACP) optical phase modulator introduces zero propagation delay. An optical field is modulated by an electromagnetic field. Within the ACP modulator, the optical field is propagated in an opposite direction to the propagation direction of the electromagnetic field. The electromagnetic field is attenuated within the ACP modulator. In an example embodiment, the length of the modulator is greater than the attenuation length of the electromagnetic field.