A low loss high performance filter structure

An improved structure for low loss, sharp cutoff, high-rejection filters has been developed. Center frequencies as high as 1500 MHz can be realized with standard optical processing techniques. Relative bandwidths of up to 0.67 K² are achievable. Data are presented for 900-MHz filters on 128° YX-LiNbOI₃ and 950-MHz filters on 36° YX-LiTaO₃ each having 3% and 1.6% relative bandwidths. 50-dB out-of-band rejection, and <6-dB insertion loss. By simple scaling of the designs to a 0.65-μm minimum linewidth, a center frequency of 1.4 GHz can be achieved on LiNbO₃ and 1.5 GHz on LiTaO₃