Nano-photonic crystal waveguides for ultra-compact tunable true time delay lines

Abstract

Nanophotonics including photonic crystals promises to have a revolutionary impact on the landscape of photonics technology. Photonic crystal line defect waveguides show high group velocity dispersion and slow photon effect near transmission band edge. By using photonic crystal waveguides to build true time delay based phased array antenna or other optical signal processing systems, the length of the tunable true time delay lines can be dramatically reduced inversely proportional to group velocity dispersion in dispersion enhanced system architecture or reduced inversely proportional to group index in slow photon enhanced system architecture. The group index of the fabricated silicon photonic crystal line defect waveguide is experimentally demonstrated as high as 40 at optical wavelength around 1569 nm. The group velocity dispersion of the fabricated silicon photonic crystal line defect waveguide is as high as 50 ps/nm.mm at wavelength around 1569 nm, which is more than 10 7 times the dispersion of the standard telecom fiber (D = 3 ps/nm.km). Due to the integration nature of photonic crystals, system-on-chip integration of the true time delay modules can be easily achieved.