We present a novel tunable wavelength filter that is based on volume holograms recorded by the interband photorefractive effect. An acousto-optic deflector is used to control the direction of the recording beams and the spacing of the photorefractive grating. Narrow bandwidths (FWHM = 0.13 nm) allowing a channel spacing of 50 GHz required for DWDM applications as well as fast tuning times in the order of a few hundred microseconds are achieved. The demonstrated tuning range of the filter is 1 nm, but can be enlarged to cover the entire spectral range of Erbium doped fiber amplifiers (~ 40 nm). Experiments were performed with pure potassium niobate crystals. With the same approach, however, other crystals that exhibit interband photorefraction at visible wavelengths can be used for tunable filters as well.
© 2003 Optical Society of AmericaPDF Article