Analysis of the steady-state photorefractive harmonic gratings

VAVELIUK, P.; RUIZ, B.; BOLOGNINI, N.

PHYSICAL REVIEW B

AMER PHYSICAL SOC

Año: 1999 vol. 59 p. 10985 - 10991

1098-0121

The steady-state exact solution for the higher harmonic gratings that synthesize the space-charge field are derived without restrictions within the Kukhtarev model. This allows us to know exactly the behavior of the harmonic amplitudes in terms of main parameters and the space-charge field spatial distribution. The amplitudes of the several gratings were found not to depend on the mean intensity of the fringe pattern in a typical cw range. With respect to the modulation depth m, the dependence of each ν-order harmonic amplitude is rigorously established as mν. Also, regions of quite different behavior in terms of the grating spacing are identified and analyzed. From this analysis, it is emphasized that the higher gratings tend to appear more strongly for materials with smallest ratio of donors traps, and for increasing values of both modulation depth, and spacing grating. Also, the higher gratings behavior in terms of applied field is analyzed. The relative importance of high harmonics is more evident for smallest values of the external field.