High-frequency narrow-band single-mode fiber-optic transversal filters

A cascade synthesis procedure for constructing high frequency narrow-band (or high quality factor) single-mode optical fiber transversal filters using
j \times j (j \geq 2)
bidirectional couplers is reported. Design and analysis of the cascade filters are described. Experimental results of many fabricated cascade filters with tap numbers up to 256 and the first-order passband frequencies up to 3.25 GHz are consistent with the mathematical analysis.