A Spatial-Distance-Controllable Demultiplexer Using a Chirped Volume Holographic Grating

In this letter, we introduce a demultiplexer with a function of controlling spatial distance based on a chirped volume holographic grating. The chirped grating is recorded by illuminating a photopolymer film under the interference of convergent and divergent beams. The theoretical and experimental results show that the position of the focused points of the diffracted beam at the readout stage depends on the distance between the grating and the output lens. This characteristic can be utilized to control the channel spacing and spatial distance in the dense wavelength-division-multiplexing demultiplexer.