We report on the demonstration of a simple, passive, alignment‐free retromodulator/conjugator. By applying a time‐varying electric field across a self‐pumped phase conjugate mirror, simultaneous wave front reversal and temporal modulation encoding occur within the same volume. With modest signal fields (∼400 V/cm), we observe >90% depth‐of‐phase modulation, with a measured bandwidth in excess of 1 MHz (scalable to >10 GHz), and with excellent conjugation fidelity. We also demonstrate, for the first time, self‐pumped conjugation using a 45°‐cut crystal of BaTiO3 with improved performance: 62% conjugate reflectivity, 100% depth‐of‐phase modulation at ∼120 V/cm, and faster conjugate‐wave build‐up time (by a factor of ∼3). Applications of these devices to high modulation‐index and high optical‐power‐handling modulators, remote fiber sensors, and mode‐locked phase conjugate resonators are discussed.