title: Photochemistry of refractive index structures in poly(methyl methacrylate) by femtosecond laser irradiation.
abstract: Femtosecond, subablation threshold photomodification of poly(methyl methacrylate) (PMMA) at 387 nm is explored to enable fabrication of optical components. Volatile fragment analysis (thermal desorption gas chromatography-mass spectrometry) and molecular weight distribution monitoring (size exclusion chromatography) suggest photochemical modification, involving direct cleavage of the polymer backbone and propagation via chain unzipping under formation of monomers, similar to the pyrolytic degradation of PMMA. Waveguides were produced in undoped, clinical-grade PMMA, showing an increased refractive index in the laser focal region (Dnmax=4x10(-3)).
authors.affiliation: Centre for Instrumentation and Analytical Science, The University of Manchester, UK.
authors.forename: Alexandra
authors.initials: A
authors.lastname: Baum
authors.forename: Patricia J
authors.initials: PJ
authors.lastname: Scully
authors.forename: Maria
authors.initials: M
authors.lastname: Basanta
authors.forename: C L Paul
authors.initials: CL
authors.lastname: Thomas
authors.forename: Peter R
authors.initials: PR
authors.lastname: Fielden
authors.forename: Nicholas J
authors.initials: NJ
authors.lastname: Goddard
authors.forename: Walter
authors.initials: W
authors.lastname: Perrie
authors.forename: Paul R
authors.initials: PR
authors.lastname: Chalker