Integrated multichannel OADMs using polymer Bragg grating MZIs

We report the first fabrication of Bragg-grating-based multichannel optical add/drop multiplexers (OADMs) in planar polymers. The filters were designed by cascading multiple stages of single-channel multi-/demultiplexers. Each stage consists of a Mach-Zehnder interferometer (MZI) with a Bragg grating across its arms. The 3-dB couplers in each MZI are multimode interference (MMI) couplers. We fabricated the first tapered MMI couplers, which provide compactness. The gratings were printed photochemically, achieving index differences as high as 10^-3 and reflectivities as large as 33 dB. The 3-dB bandwidth is about 0.2 nm. Apodization was used to reduce sidelobes in the reflection spectrum. Four-channel OADMs were produced and exhibited the proper 400-GHz channel separation and ITU grid wavelength alignment, as well as excellent channel isolation and uniform channel response