The optical dense comb filters are indispensable components for dense wavelength multiplexing systems. In this paper, a novel and basic method is proposed to realize optical dense comb filters. The reflection spectrum of sampled fiber Bragg grating is analyzed after applying a phase shifting technique that varies the phase of the grating. The spectral densification and shifting effects of periodic phase shifts are investigated and it is shown that desired amount of channel multiplying can be provided by using appropriate value of densification factor. Moreover, a quantization technique is proposed in order to reduce the phase shifting series which complicated by the increase of densification factor. (C) 2007 Elsevier Inc. All rights reserved.