The transfer characteristics of parallel-cascaded arrays of generalized two-port microring networks with interstage phase shifts are investigated for potential applications in spectral engineering. It is found that these structures can exactly realize optical transfer functions with quadrantal symmetric zeros if the microring networks are even-symmetric. The proposed filter architectures have advantages in that the microring networks have all-positive coupling coefficients, and the array can always be reduced to the canonical form that contains only one interstage π phase-shift element. A method for exactly synthesizing cascaded symmetric microring networks based on the transfer matrix factorization technique is presented, and an example of an eighth-order generalized Chebyshev filter is given to illustrate the application of these microring lattice architectures for realizing very high-order optical transfer functions.
© 2008 Optical Society of America
Original Manuscript: May 23, 2008
Manuscript Accepted: June 26, 2008
Published: August 20, 2008
Ashok M. Prabhu, Hai Ling Liew, and Vien Van, "Generalized parallel-cascaded microring networks for spectral engineering applications," J. Opt. Soc. Am. B 25, 1505-1514 (2008)