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Inverse design and demonstration of a compact and broadband on-chip wavelength demultiplexer


Integrated photonic devices are poised to play a key role in a wide variety of applications, ranging from optical interconnects1 and sensors2 to quantum computing3. However, only a small library of semi-analytically designed devices is currently known4. Here, we demonstrate the use of an inverse design method that explores the full design space of fabricable devices and allows us to design devices with previously unattainable functionality, higher performance and robustness, and smaller footprints than conventional devices5. We have designed a silicon wavelength demultiplexer that splits 1,300 nm and 1,550 nm light from an input waveguide into two output waveguides, and fabricated and characterized several devices. The devices display low insertion loss (2 dB), low crosstalk (<−11 dB) and wide bandwidths (>100 nm). The device footprint is 2.8 × 2.8 μm2, making this the smallest dielectric wavelength splitter.

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Figure 1: Overview of the inverse design process.
Figure 2: The compact wavelength demultiplexer designed by the inverse design algorithm.
Figure 3: SEM images of the fabricated wavelength demultiplexer.
Figure 4: S-parameters for the device, where Sij is the transmission from port j to port i.


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This work was supported by the Air Force Office of Scientific Research Multi-University Research Initiative (programme director G. Pomrenke; grant no. FA9550-09-1-0704). A.Y.P. acknowledges support from the Stanford Graduate Fellowship. K.G.L. acknowledges support from the Swiss National Science Foundation. J.P. was supported in part by the National Physical Science Consortium Fellowship and by stipend support from the National Security Agency. The authors thank S. Boyd for his theoretical guidance and discussions regarding the optimization algorithm. In addition, the authors thank J. Poon for the donation of the SOI wafer used to fabricate the devices.

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A.Y.P. designed, simulated, fabricated and measured the devices. J.L. developed the inverse design algorithm and software. K.G.L. assisted in building the measurement set-up. J.P. contributed to the simulation software. T.B. provided theoretical and experimental guidance. J.V. supervised the project. All members contributed to the discussion and analysis of the results.

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Correspondence to Jelena Vučković.

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The authors declare no competing financial interests.

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Piggott, A., Lu, J., Lagoudakis, K. et al. Inverse design and demonstration of a compact and broadband on-chip wavelength demultiplexer. Nature Photon 9, 374–377 (2015).

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