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A device concept for laterally extracting selected wavelength from an optical signal travelling along a waveguide, for operation in metropolitan area networks, is presented. The signal on the fundamental mode of a multimode photonic crystal waveguide is coupled to a higher-order mode, at a center frequency that spatially depends on the slowly varying guide parameters. The device is compact, intrinsically fault-tolerant, and can split any desired fraction of the signal for monitoring purpose. Characterizations by the internal light source technique validate the optical concept while an integrated device with four photodiodes qualifies its potential with respect to real-world applications

Articles you may be interested inFabrication of two-and three-dimensional photonic crystals of titania with submicrometer resolution by deep xray lithographyWe report on the fabrication of diamond-like photonic structures in PMMA resist and their use as porous templates for transferring three-dimensional patterns to metals or dielectrics. Following the original ''three drilling holes'' approach first proposed by Yablonovitch, we used three consecutive exposures of PMMA resist to an x-ray beam through a triangular lattice of holes. A submicronic patterning was thus obtained in thick PMMA layers ͑Ͼ6 m͒. Optical characterizations of 1.3 m period templates showed a well-defined photonic gap in the midinfrared. The pattern transfers from the PMMA templates to a metal ͑copper͒ and a high refractive index dielectric ͑titania͒ were achieved by the electrodeposition and sol-gel filling techniques, respectively. Three-dimensional metallic structures of 1.3 m lattice constant were obtained with extreme regularity over a thickness of ϳ6 m, thereby providing a way to build submicrometer photonic band gap materials for optical wavelengths.