Patent ID: 8218922

Claim:
An optical device for dispersion compensation of wavelength division multiplexed channels within a predetermined wavelength band, comprising: a waveguiding structure; and a grating structure formed in said waveguiding structure; characterized in that said grating structure has a Bragg frequency profile that is divided into contiguous periods, wherein the Bragg frequencies within each period vary between a lower Bragg frequency and an upper Bragg frequency, said lower and upper Bragg frequencies for each period both corresponding to wavelengths outside of said predetermined wavelength band, wherein the Bragg frequency profile of the grating structure is a sum of a background profile corresponding to a chirped background grating designed for dispersion compensation of one channel within said wavelength band, and a modulation profile having a monotonically varying Bragg frequency, which is reset after each period, corresponding to an extra chirp added to the background profile such that the total increment in Bragg frequency over each period is spanning at least said predetermined wavelength band, and wherein said contiguous periods have a gradually varying length along the grating structure in order to add a dispersion slope to the grating structure, and wherein a frequency dependent apodization is introduced to compensate for variations, caused by the varying period length, in the frequency window for different channels within said predetermined wavelength band.