Broadband waveguide polarizers based on the anisotropic optical constants of nanocomposite films

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Abstract
Thin metal-dielectric nanocomposite films (30 mm thick) deposited on ion-exchanged glass waveguides form high extinction polarizers. The polarizing properties are due to the absorption bands of the surface plasmon modes in the nonspherical, nanometer-size silver particles which are embedded in a glass host. The absorption bands of the surface plasmon modes are strongly dependent on the shape and orientation of the nonspherical particles. We demonstrate wavelength tuning and broadening of the polarization band in the silver nanocomposite film by altering the particle shape distribution. We have fabricated waveguide polarizers with extinction ratios 1/spl times/10/sup -4//mm over the wavelength range of 800-1100 nm. An unusual feature of the polarizer is that it passes the TM polarization. The optical constants of the nanocomposite film were calculated by Maxwell-Garnett theory. The nanocomposite films have a large birefringence (/spl sim/0.5) and highly anisotropic extinction coefficients.