We utilize the anomalous dispersion of planar photonic crystals near the dielectric band edge to control the wavelength-dependent propagation of light. We typically observe an angular swing of up to 10°as the inp...We utilize the anomalous dispersion of planar photonic crystals near the dielectric band edge to control the wavelength-dependent propagation of light. We typically observe an angular swing of up to 10°as the input wavelength is changed from 1290 nm to 1310 rim, which signifies an angular dispersion of 0.5°/am （＂Superprism＂ phenomenon）. Such a strong angular dispersion is of the order required for WDM systems. By tuning the incident angle, light beams with up to 20° divergence were collimated over a 25 nm （1285 nm to 1310 nm） bandwidth using a triangular lattice （＂Supercollimator＂ phenomenon）. The wavelength collimating range can be extended from 25 nm to 40 nm by changing the lattice from triangular to square. These two devices can be realized in the same configuration, simply by tuning the wavelength. Sources of loss are discussed.展开更多
It is clarified by experimental examination and theoretical analysis that the transformation of crystal moorphology of the eutectic Al-Cu alloy composite-in-situ seems to be judged by not only the constitutional super...It is clarified by experimental examination and theoretical analysis that the transformation of crystal moorphology of the eutectic Al-Cu alloy composite-in-situ seems to be judged by not only the constitutional supercooling proposed in previous literatures but also the supercooling due to the effect of curved surfaces at the solidifying from.The greater entropy of fusion and the tendency to faceted face are important features of the non-metallic phase,which may con- tribute to the leading,role of the phase during solidification.It might be the change of leading phase that changes the morphology of crystals.展开更多
文摘We utilize the anomalous dispersion of planar photonic crystals near the dielectric band edge to control the wavelength-dependent propagation of light. We typically observe an angular swing of up to 10°as the input wavelength is changed from 1290 nm to 1310 rim, which signifies an angular dispersion of 0.5°/am （＂Superprism＂ phenomenon）. Such a strong angular dispersion is of the order required for WDM systems. By tuning the incident angle, light beams with up to 20° divergence were collimated over a 25 nm （1285 nm to 1310 nm） bandwidth using a triangular lattice （＂Supercollimator＂ phenomenon）. The wavelength collimating range can be extended from 25 nm to 40 nm by changing the lattice from triangular to square. These two devices can be realized in the same configuration, simply by tuning the wavelength. Sources of loss are discussed.
文摘It is clarified by experimental examination and theoretical analysis that the transformation of crystal moorphology of the eutectic Al-Cu alloy composite-in-situ seems to be judged by not only the constitutional supercooling proposed in previous literatures but also the supercooling due to the effect of curved surfaces at the solidifying from.The greater entropy of fusion and the tendency to faceted face are important features of the non-metallic phase,which may con- tribute to the leading,role of the phase during solidification.It might be the change of leading phase that changes the morphology of crystals.
