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Surface grating couplers are fundamental building blocks for coupling the light between optical fibers and integrated photonic devices. However, the operational bandwidth of conventional grating couplers is intrinsically limited by their wavelength-dependent radiation angle. The few dual-band grating couplers that have been experimentally demonstrated exhibit low coupling efficiencies and rely on complex fabrication processes. Here we demonstrate for the first time, to the best of our knowledge, the realization of an efficient dual-band grating coupler fabricated using 193 nm deep-ultraviolet lithography for 10 Gbit symmetric passive optical networks. The footprint of the device is 17 × 10 µm. We measured coupling efficiencies of −4.9 and −5.2 dB with a 3-dB bandwidth of 27 and 56 nm at the wavelengths of 1270 and 1577 nm, corresponding to the upstream and downstream channels, respectively.

Integrated microspectrometers implemented in silicon photonic chips have gathered a great interest for diverse applications such as biological analysis, environmental monitoring, and remote sensing. These applications often demand high spectral resolution, broad operational bandwidth, and large optical throughput. Spatial heterodyne Fourier-transform (SHFT) spectrometers have been proposed to overcome the limited optical throughput of dispersive and speckle-based on-chip spectrometers. However, state-of-the-art SHFT spectrometers in near-infrared achieve large optical throughput only within a narrow operational bandwidth. Here we demonstrate for the first time, to the best of our knowledge, a broadband silicon nitride SHFT spectrometer with the largest light collecting multiaperture input (320 × 410 µm) ever implemented in an SHFT on-chip spectrometer. The device was fabricated using 248 nm deep-ultraviolet lithography, exhibiting over 13 dB of optical throughput improvement compared to a single-aperture device. The measured resolution varies between 29 and 49 pm within the 1260-1600 nm wavelength range.

Silicon nitride (SiN) waveguides provide a substantially lower index contrast, thermo-optic coefficient, and reduced birefringence compared to silicon-on-insulator waveguides. These properties make SiN a prominent candidate for implementation of ultra-wideband dual-polarization photonics circuits with a great potential for datacom applications. State-of-the-art SiN power splitters are still hampered in terms of either bandwidth or single-polarization operation. Here, we propose to overcome these limitations by exploiting modal and waveguide symmetry engineering in a single-mode slot waveguide. This topology prevents mode-beating, while granting symmetric power splitting for both polarizations. Experimental characterization of the fabricated device shows low loss (<0.62dB) and imbalance (<0.6dB) within an unprecedented bandwidth of 420 nm (1.26–1.68 µm).