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 America
P. Dittrich, G. Montemezzani, and P. Günter, "Interband Photorefraction for Tunable Optical Filters at Telecom Wavelengths," in Photorefractive Effects, Materials, and Devices, P. Delaye, C. Denz, L. Mager, and G. Montemezzani, eds., Vol. 87 of OSA Trends in Optics and Photonics (Optical Society of America, 2003), paper 620.
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