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We describe a design methodology for optimizing an ultra-compact 3 μm long circular high contrast grating (HCG) reflector. A multi-stage optimization process involving parameter optimization (PO) followed by seeded topology optimization (TO) is demonstrated to design a device with performance better than that achieved with PO or TO alone. The device is designed for a foundry process and offers reflection commensurate with waveguide-based Bragg gratings with a significantly higher bandwidth in an ultra-compact footprint. A peak reflectance of 98.9 % was simulated centered at 1569 nm with a minimum reflectance of 97.9 % over C-band.
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We present compact, low-loss silicon nitride mode converters designed using topology optimization and fabricated on a commercial silicon foundry. We experimentally demonstrate efficient mode conversion (-0.32 dB for TE00 to TE01 and -0.52 dB for TE00 to TE02), both within 0.4 dB of simulation.more » « less
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For photonic signal transport in multiple-GHz, waveform-sensitive RF transport applications, it will be shown that digital-over-fiber enables superior SNR performance versus analog-over-fiber. However, for SWaP-constrained systems, the latter can provide a viable solution with minimal SNR penaltymore » « less
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We designed a compact integrated Silicon Nitride 1 x 3 balanced optical power splitter using density-based topology optimization with built-in fabrication constraints. We experimentally validate our design on a commercial foundry process with a splitting ratio of 30-36-33 % and an insertion loss of 2.48 dB across two wafersmore » « less
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We present a novel device-design methodology that produces interferometrically robust photonic integrated circuits on commercial foundry platforms. This new approach, which we call phaseinjected topology optimization, leverages reciprocity to both reduce the computational load and condition the corresponding optimization problem and is compatible with existing adjoint-based design frameworks. We experimentally validate our methodology by designing, fabricating, and testing a 90◦ optical hybrid that operates over C-band and occupies just 8 μm × 8 μm. We measured our device across three different wafers, and observe < ±7◦ of random variability, and a net -10◦ systematic phase deviation between simulation and experiment across all four output arms.more » « less
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Abstract—We experimentally demonstrate normal-incidence grating couplers designed using topology optimization to couple into multi-core fiber. The insertion loss of the polarizing and polarization demultiplexing gratings was –5.5 dB and –7.7 dB, which is within 0.8 dB of the performance obtained using a fiber arraymore » « less
