Enhanced photoinduced birefringence in polymer microcavities

We investigate photoinduced birefringence in functionalized polymer microca vities illuminated by a visible polarized cw laser beam. The cavity studied in this experiment consists of an assembly of two Bragg mirrors embedding a polymer film with tethered azobenzene dyes. Linearly polarized light indu ces orientationally selective excitation of the chromophore guests, resulti ng in optical anisotropy of the film. The mechanism of the phenomenon is ba sed on random-to-axial statistical reorientation of the azochromophores fol lowing repetitive trans-cis-trans photoisomerization cycles. The resulting birefringence is inferred from analysis of the spectral shifts of the cavit y Fabry-Perot longitudinal modes as a result of illumination. A large value of the birefringence of the order of 10(-2) is noted after currently unopt imized durations of the order of 30' in the 1.3-1.5 mu m range with possibl e applications in optical storage at WDM telecom-compatible wavelengths. (C ) 2000 American Institute of Physics. [S0003-6951(00)01641-7].