Photosensitivity and grating development in trans-4-stilbenemethanol-doped poly(methyl methacrylate) materials

✍ Scribed by JianMing Yu; XiaoMing Tao; HwaYaw Tam; DongXiao Yang; M. Suleyman Demokan

• Book ID: 103872607
• Publisher: Elsevier Science
• Year: 2006
• Tongue: English
• Weight: 342 KB
• Volume: 265
• Category: Article
• ISSN: 0030-4018
• DOI: 10.1016/j.optcom.2006.03.029

✦ Synopsis

This paper reports the photosensitivity of poly(methyl methacrylate) (PMMA) and its copolymer doped with trans-4-stilbenemethanol. UV irradiation of the doped-PMMA at 325 nm induced the trans-to cis-isomerization of the dopant. This process was confirmed by 1 H NMR spectra of trans-4-stilbenemethanol in CDCL 3 solvent before and after irradiation. The isomerization can be initiated by the irradiation with an intensity of 0.62 mW/cm 2 . Photo-induced refractive index change of À0.0024 was obtained when a PMMA copolymer film doped with 5.1 wt% dopant was exposed to 325 nm light. Lorentz-Lorenz equation was used to estimate the refractive index of a trans-4-stilbenemethanol-PMMA composite and a trans-4-stilbenemethanol-PMMA copolymer composite from the mole refraction and van der Waals volume of each component. A slight elevation of molecular packing coefficient (K) for PMMA and its copolymer containing the dopant implies a denser aggregation as compared to the polymer without the dopant. Long period gratings were created in doped-PMMA films and doped-PMMA copolymer fibers using amplitude mask technique. Gratings were confirmed by microscopic observation and diffraction patterns.