Photorefractivity in a bi-functional polymer nanocomposites sensitized by CdS nanoparticle

Abstract

We report an organic/inorganic hybridized nanocomposite consisting of a bi-functional poly(N-vinyl)-3-[p-nitrophenylazo]carbazolyl serves as a polymeric charge-transporting and second-order nonliner optical matrix, and CdS nanoparticles as photosensitizers to manifest photorefractive (PR) effect. The unpoled PVNPAK film exhibits a second harmonic generation (SHG) coefficient of 4.7 pm/V due to the possibility of self-alignment of the azo chromophore. Significant enhancement of photoconductivity is noticed with the increase of CdS nanoparticles concentration. The photorefractive property of the polymer nanocomposites were determined by two-beam coupling (TBC) experiment. The TBC gain and diffraction efficiency of 11.89 cm -1 and 3.2% were obtained for PVNPAK/CdS at zero electrical field.

A novel multi-cavity Helmholtz muffler*

“…[2] Controlling the low-frequency noise to avoid being detected by the enemy is the key to improving the stealth performance of the submarine. [3] However, it is difficult to control the noise of submarines from the source for many complex reasons, designing a kind of muffler [4] with low frequency noise reduction characteristic is very important.…”