Design of Microwave Photonic Filter Using Zero‐Pole Placement Method With FBG Based Delay Lines

ABSTRACT A novel technique for design of microwave photonic filter using fiber Bragg grating based delay lines with zero‐pole placement method has been proposed and demonstrated. The concept of linear phase based finite impulse response (FIR) filter has been utilized. The proposed work focuses on technique to compute the filter‐tap coefficients for general delay‐line based microwave photonic filter structures for a desired spectral response. The filter coefficients have been obtained as real and positive and treated as the reflectivities of the FBGs connected in cascade. The low‐pass and multi‐band pass microwave photonic filter have been realized for operation in 0.2–25 GHz microwave frequency range. The filter performance has been analyzed in terms of bandwidth, order, and size of the filter. The size of the core component of the filter or overall FBG‐based delay link is obtained as 1–10 cm. The filter has been simulated both theoretically and experimentally and good agreement is achieved. The proposed design technique can also be applied for infinite impulse response (IIR) filters and as well as all classes of filters. The compact sized filter can be used for photonic‐integrated circuits.