Enhancement of bulk second-harmonic generation from silicon nitride films by material composition.

We present a comprehensive tensorial characterization of second-harmonic generation from silicon nitride films with varying compositions. The samples were fabricated using plasma-enhanced chemical vapor deposition, and the material composition was varied by the reactive gas mixture in the process. We found a six-fold enhancement between the lowest and highest second-order susceptibility, with the highest value of approximately 5 pm/V from the most silicon-rich sample. Moreover, the optical losses were found to be sufficiently small (below 6 dB/cm) for applications. The tensorial results show that all samples retain in-plane isotropy independent of the silicon content, highlighting the controllability of the fabrication process.

Study of surface relief gratings on azo organometallic films in picosecond regime.

Materials for optical data storage and optical information processing must exhibit good holographic properties. Many materials for these applications have been already proposed. Here we describe a grating inscription process characterized by short inscription time and long-time stability. A series of ruthenium-acetylide organometallic complexes containing an azobenzene fragment were synthesized. Photo-induced gratings were produced by short pulse (16 ps, 532 nm) laser irradiation. The surface relief gratings formed at the same time were observed by atomic force microscope. In this work, we highlight the short inscription times brought into play as well as the good temporal stability of these gratings stored at room temperature. We study the influence of the polarization states and the light intensity of writing beams on the dynamics of the surface relief gratings formation and we compare these results with those of a known representative of azobenzene derivative (Disperse Red 1). Lastly, we show that it is possible to write two-dimensional surface relief gratings.

Grating inscription in picosecond regime in thin films of functionalized DNA.

Polymers containing azo-benzene groups are useful holographic recording materials. In these materials the efficient mixed amplitude and phase gratings, frequently accompanied with photoinduced-surface relief gratings, can be inscribed with polarized laser light. The light-induced trans-cis-trans photoisomerization of azo-benzene groups is responsible for optical anisotropy in such systems. The aim of the present work is to study the dynamics of grating inscription in Disperse Red 1 doped deoxyrbonucleic acid- hexadecyltrimethylammonium material (DR1-DNACTMA) using 16 ps laser pulses (532 nm, 1.3 mJ). Results are compared with that obtained for other polymeric matrices loaded with DR1. The dynamics of the grating growth, due to repeated pulses from picosecond laser with 10 Hz repetition rate, was probed by measuring the intensity of the first order of diffraction of a cw He-Ne. We report results in function of the light polarization of writing beams. In this paper we present the first results of the grating inscription in functionalized DNA (in the picosecond pulse regime).