Laser-induced holographic surface relief gratings on nonlinear optical polymer films

TLDR

The authors fabricated surface relief gratings on a second‑order nonlinear polymer film by exposing it to polarized 488‑nm Ar⁺ laser light, then characterized the resulting 120‑nm‑deep structures with atomic force microscopy and demonstrated orthogonal grating recording and wavelength‑dependent diffraction efficiency. The laser‑induced gratings exhibited large amplitudes, with a typical depth of 120 nm (≈20 % of the film thickness), and gold‑coated gratings showed measurable diffraction efficiency that varied with wavelength, confirming the feasibility of orthogonal grating recording.

Abstract

We report observation of holographic surface relief gratings with relatively large amplitude on a second order nonlinear optical polymeric material. Surface relief gratings on these polymer films were created upon exposure to polarized Ar+ laser beams at 488 nm without any subsequent processing steps. The surface structure of the relief gratings was investigated by atomic force microscopy. The depth of the surface relief in a typical case was 120 nm which is approximately 20% of the original film thickness. The diffraction efficiency of gold-coated gratings was investigated as a function of wavelength and capability of recording orthogonal gratings on the same film was demonstrated.