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In terms of the coupled mode theory, novel formulas of the transfer functions are presented for a microring resonator array, which consists of multiple series-cascaded filter elements, and each of them contains double parallel-cascaded identical microrings. By using these formulas, we can analyze transmission characteristics for such a polymer device. Simulated results show that when some parameters are selected properly, the box-like spectral response can be formed, which is flat and steep, and the sidelobes and the cross talk can be dropped efficiently. The effects of manufacturing tolerances on the transmittance are discussed, which result in the shift of the transmission spectrum of the device.

Based on formulas presented for the amplitude coupling ratio and the transfer function, transmission characteristics are analyzed and parameters are optimized for a polymer cross-grid array of microring resonant wavelength multiplexers around the central wavelength of 1.550918 μm with wavelength spacing 1.6 nm. In the design of the device, by means of selecting a resonant order m=95 and introducing a resonant order increment of adjacent filter elements Δm=2, we increase the ring radius difference of adjacent filter elements ΔR from 17 nm (for the case of Δm=0) to 337 nm. Calculated results show that the 3‐dB bandwidth is about 0.2 nm, the ratio between the −1- and −10‐dB bandwidths is about 0.22, the insertion loss is less than 0.5 dB, and crosstalk is below −39 dB for each of the eight horizontal output channels.

Based on formulas presented, optimization design is performed and the effects of manufacturing tolerances on transmission characteristics are analyzed for a polymer microring resonant wavelength multiplexer around the central wavelength of 1.550918 μm with wavelength spacing 1.6 nm. Modeling results show that the insertion loss is less than 0.55 dB and crosstalk is less than −21 dB for each of eight vertical output channels of the designed device without tolerances. Some manufacturing tolerances result in a shift of the transmission spectrum and lead to increases of the inserted loss and crosstalk over the design case without tolerances. © 2005 Society of Photo-Optical Instrumentation Engineers.