Forced-oscillator model of a photorefractive space-charge field that is due to carrier population variation

Yuan, BH Sun, XD Zhou, ZX Hou, CF Li, Y Jiang, YY Li, CF

Bh. Yuan et al., Forced-oscillator model of a photorefractive space-charge field that is due to carrier population variation, J OPT SOC B, 18(9), 2001, pp. 1342-1350

24

INGLESE

Article

Apllied Physucs/Condensed Matter/Materiales Science","Optics & Acoustics

JOURNAL OF THE OPTICAL SOCIETY OF AMERICA B-OPTICAL PHYSICS

0740-3224 → ACNP

18

9

2001

1342 - 1350

ISI

0740-3224(200109)18:9<1342:FMOAPS>2.0.ZU;2-M

Without using the usual assumption of free-carrier quasi-static distributio n, we derive a forced-oscillation equation with damping to describe the bui ldup of a fundamental harmonic space-charge field in inorganic photorefract ive (PR) crystals. Thus the PR holographic records of static gratings and d ynamic gratings can be understood in terms of the usual vibration theories. The solution of the equation is biexponential and encompasses two time con stants that had been observed in some PR materials. The ratio of the two ti me constants is calculated as a function of experimental parameters, such a s the total incident intensity and the applied electric field, to prove the applicability of our model. Results show that the difference between the t wo time constants may be so small that neither of the constants can be negl ected. Additionally, the resonance frequencies obtained from the two models for the moving grating are compared, and a figure of merit Q is defined to describe the resonance properties. All the results show that our model can be applied to general cases. (C) 2001 Optical Society of America.