Microfluidics and photonic crystals may yield optical integrated circuits

Researchers at the European Laboratory for Non-Linear Spectroscopy (Firenze, Italy), the University of Trento (Trento, Italy), and the University of Paderborn (Paderborn, Germany) have used precisely controlled microscopic quantities of liquid (on the order of a femtoliter) to locally modify refractive indices in 2-D photonic crystals-a potential method for fabricating the optical equivalent of integrated circuits.

Jan 1st, 2007

Researchers at the European Laboratory for Non-Linear Spectroscopy (Firenze, Italy), the University of Trento (Trento, Italy), and the University of Paderborn (Paderborn, Germany) have used precisely controlled microscopic quantities of liquid (on the order of a femtoliter) to locally modify refractive indices in 2-D photonic crystals-a potential method for fabricating the optical equivalent of integrated circuits. A solution of water and the organic dye Rhodamine 6G (with refractive index high enough to introduce permitted states into the photonic bandgap) was introduced into selected pores of photonic crystal via capillary action using a micropipette positioned with 0.1 µm precision with respect to the photonic-crystal surface. A custom-built confocal laser-scanning microscope was used to monitor the process, assisted by the photoluminescence of the Rhodamine dye.

Calculations confirmed that the researchers fabricated optical-resonator and waveguide structures as intended. Inserting liquids of specific refractive index and nonlinear constant, local light sources, and liquid crystals to tune the refractive index externally is expected to enable pixel-by-pixel fabrication of erasable and rewritable optical components, such as waveguides, active elements, and sources, as well the assembly of such optical components into integrated optical circuits. Contact Francesca Intonti at intonti@lens.unifi.it.

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