Polarization independent, integrated optical, acoustically tunablewavelength filters/switches with tapered acoustical directional coupler

Enhanced sidelobe suppression of the filter characteristics of tunable acousto-optical mode converters in LiNbO₃ has been achieved using for the first time tapered acoustical directional couplers. A sidelobe suppression of more than 15.5 dB could be demonstrated in a single stage device. By combining the mode converter with two integrated optical polarization splitters a polarization independent filter/wavelength selective switch has been fabricated with less than 3 dB intrinsic insertion loss, a polarization dependence of less than 1 dB, and a sidelobe suppression exceeding 14 dB