Single pulse phase conjugation by self-pumped four-wave mixing in BaTiO3

Self-pumped phase conjugation1 can be used to generate automatically self-aligned counterpropagating pump waves for four-wave mixing in a single crystal of BaTiO3.2 Here we give a physical explanation for previously unreported features of what we term "self-pumped four-wave mixing" in a BaTiO3 crystal, by comparing experimental results obtained using a train of nanosecond pulses with a steady-state photorefractive four-wave mixing theory. From this physical explanation we have optimized a self-pumped four-wave mixing geometry to produce the phase conjugate of a single pulse.