Low-loss demonstration and refined characterization of silicon arrayed waveguide gratings in the near-infrared

E. J. Stanton, N. Volet, and J. E. Bowers
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(a) Diagram of the AWG-ring with complex amplitudes Ei and Et of the input and output guided electric fields. Coupling between the bus and ring waveguides is characterized by ˜  and ˜ . (b) Schematic of the AWG design parameters.
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Journal/Conference Name
Optics Express
Vol. 25, No. 24, pages 30651-30663

A resonator is characterized with two cascaded arrayed waveguide gratings (AWGs) in a ring formation. From this structure, the on-chip transmittance of a single AWG is extracted, independent of coupling efficiency. It provides improved measurement accuracy, which is essential for developing AWGs with extremely low loss. Previous methods normalize the off-chip AWG transmittance to that of a reference waveguide with identical coupling, leading to an uncertainty of ∼14 % on the extracted on-chip AWG transmittance. It is shown here that the proposed “AWG-ring” method reduces this value to ∼3 %. A low-loss silicon AWG and an AWG-ring are fabricated. Channel losses with <2 dB are found, with a crosstalk per channel approaching −30 dB. Such an efficient wavelength multiplexing device is beneficial for the integration of spectroscopic sensors, multi-spectral lasers, and further progress in optical communication systems.

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Research Areas
Silicon Photonics