Infrared dielectric mirrors based on thin film multilayers of polystyrene and polyvinylpyrrolidone

Abstract

Thin film polymer multilayers were prepared by spin coating alternating layers of polystyrene and polyvinylpyrroli- done. Samples with 10, 20, 30, 40, and 50 layers were prepared with individual layer thickness values in the range 223-508 nm. These samples were measured using a Fourier transform infrared spectrometer and were found to display narrow photonic band gaps (∼0.04 to 0.06m wide) in their spectral response over the wavelength range 1.6 − 2.6m. The position of the photonic band gaps was controlled by varying the thickness of the individual lay- ers within the multilayer structures. This was achieved by varying the spin speed used during the deposition of the polymer layers. The peak reflectance of the multilayers was controlled by vary- ing the number of layers within the multilayer samples giving values in the range 20-80% (corresponding to transmittances of 80-20%). Calculated transmittance spectra were also obtained using an optical transfer matrix method. These calculated spec- tra were shown to be in good agreement with the experimental data obtained. These experiments demonstrate a facile approach to the production of low cost dielectric mirrors that have tai- lored photonic properties over a range of wavelengths that are currently important for applications in fibre optic based telecom- munications. © 2011 Wiley Periodicals, Inc. J Polym Sci Part B: Polym Phys 49: 732-739, 2011