<title>Observation of Wood's anomalies in phase conjugation of IR radiation on atmospheric ice films</title>

Abstract

ABSTRACT The study ofWood's anomalies in phase conjugation ofcw CO2 laser radiation on atmospheric ice films has been carried out. The enhancement up to 5 times of phase conjugated wave and itsbistable behavior, drag of resonance, damping relaxation oscillations, increasing of effectiveabsorbtivity of laser radiation have been established at Wood's anomalies of surface polaritons excitation in the +2 and +3 diffraction orders by the two-wave induced dynamic grating.Keywords: phase conjugation, Wood's anomalies, surface waves, dynamic grating 1. INTRODUCTION Conventionally, two-wave mixing under the Raman-Nath diffraction regime and phase conjugation by surfaces are considered without including any resonance with surface modes of thin films andsurfaces13. It was shown7 that at some angles of two-wave incidence on the surface Wood's anomalies can be induced. These anomalies are linked to incident wave coupling to surface waves bymeans ofhard grating ruled on the surface8'9. We have shown that analogous Wood's anomalies can bealso induced on dynamic grating (DG). These Wood's anomalies induced on the DG are closely relatedto formation of surface periodic structures (SPS) by means of single wave illumination of surface'°'11.Above intensity thresholds of SPS formation the induced SPS coincide with two-wave induced DG