an optical filter comprises a waveguide and a plurality of slanted bragg gratings written in the waveguide , wherein at least two of the slanted bragg gratings overlap one another . a method of producing an optical filter comprises the steps of passing an ultraviolet light through a first portion of a chirped phase mask onto a first portion of a photosensitive waveguide so as to form a first slanted bragg grating in the first portion of the waveguide and passing the ultraviolet light through a second portion of the chirped phase mask onto a second portion of the photosensitive waveguide so as to form a second slanted bragg grating in the second portion of the waveguide , wherein the first and second slanted bragg gratings overlap one another . a further annealing step may cause a spectrum of the filter to match a target spectrum .