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Article Abstract
An inverse-designed broadband multimode interference (MMI) coupler based on SiN waveguide is proposed. The widths of the waveguides are modulated based on an adjoint sensitivity analysis. Starting from a gray refractive index distribution, the distribution is binarized at the final design stage to enable the fabrication of the device. Only some tens of iterations are necessary to obtain converged geometry. By modulating the widths of the MMI region, the spectra become very flat over the 100-nm wavelength range. The characteristics of the device are further improved by optimizing the input and output waveguide widths, in addition to the width of the MMI region. The designed device is fabricated, and the measured transmission spectra are in excellent agreement with the calculation, showing the usefulness of the design method. Over 100-nm broadband 3-dB splitting is experimentally demonstrated.
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| http://dx.doi.org/10.1364/OL.566860 | DOI Listing |
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