Tunable Integrated Electro-Optic Wavelength Filter With Programmable Spectral Response

In this paper, we report on an integrated optical wavelength filter device in LiNbO₃ . A sequence of individually addressable polarization converters enables programmable spectral response and continuous wavelength tunability. Wavelength-selective polarization conversion is obtained using in-phase and quadrature-driven electro-optic converters. A model based on coupled-mode analysis is presented that allows to determine the filter performance. Examples of tailoring the spectral response to obtain strong sidelobe suppression and flat-top responses are discussed. Predicted theoretical results are confirmed by experiments. A 2.3 nm wide bandpass filter with more than 20 dB sidelobe suppression and a tuning range of about 20 nm are demonstrated. Moreover, even a flat-top characteristics with 4.9 nm bandwidth and about 15 dB sidelobe suppression could be demonstrated with the same device.