Wavelength-selective filter based on a hollow optical waveguide

In this paper, we describe a theoretical and experimental study of a wavelength-selective filter derived from hollow optical waveguides composed of Bragg reflectors with defect layers on a silicon substrate. The defect states of the transmission filter at wavelengths of 1519 and 1571 nm were realized using onedimensional photonic crystals (1D PCs) formed from a-Si and SiO₂. The transmission spectra of the filter waveguides and the band structure of the defect 1D PCs were calculated using the two-dimensional finite-difference time-domain and transfer matrix methods, respectively. The device exhibited the narrow bandwidths of 0.5 and 1:1 nm for wavelengths of 1571 and 1519 nm, respectively.