Self-pumped and incoherent phase conjugation in Fe-doped KNbO_3

Abstract

Self-pumped phase-conjugated reflectivities in KNbO3 crystals doped with Fe have been optimized in specially cut crystals. Without using external cavities, we have obtained reflectivities of as high as 60%. With the pump beams derived from the self-pumped phase-conjugation process, degenerate four-wave mixing buildup time is 6 s, with a reflectivity of 30%. For the first time, the double incoherent phase conjugation in KNbO3 is also reported with reflectivities of as high as 65% and buildup times of 10 s. We present what are, to our knowledge, the first experiments on quantitative investigations of the fidelity of double phase-conjugate mirrors by interferometric methods that showed the high quality of the phase-aberration correction achieved in Fe:KNbO3.