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.