Unconventional beam amplification with photovoltaic and diffusion effects in a He~+-implanted LiNbO_3:Fe waveguide

摘要

Two-wave mixing at 514.5 em is investigated in an x-cut LiNbO_3:Fe waveguide twice implanted with helium ions. The energy transfer is studied in four configurations characterized by the orientation of the optical axis and the polarization of the input waves.It is shown that, in one arrangement, the kinetics of the wave mixing consists of two parts: a transient peak attributed to the photovoltaic effect followed by a slower decay toward the stationary state for which the classic diffusion mechanism is predominant. The appearance of the photovoltaic effect is unexpected in comparison with the results found for the bulk.