Grating couplers on thin-film lithium niobate ridge waveguides were designed and fabricated using UV-laser ablation. The calculated coupling efficiency with a sinusoidal grating can be as large as 53% in a 0.5 µm thin film. The maximum grating depth we fabricated was 130nm, limiting the coupling efficiency to a theoretical value of 18%. We fabricated grating couplers on adhered ridge waveguides of 20 µm thickness. Coupling light to waveguides on thin-film lithium niobate is still challenging, and here we present a fast, cheap and reliable fabrication alternative. It will benefit the on-chip testing of integrated components developed on this novel and promising material platform.
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http://dx.doi.org/10.1364/OE.396667 | DOI Listing |
Sci Adv
January 2025
Guangdong Provincial Key Laboratory of Optical Fiber Sensing and Communications, Institute of Photonics Technology, Jinan University, Guangzhou 510632, China.
Artificial nanostructures with ultrafine and deep-subwavelength features have emerged as a paradigm-shifting platform to advanced light-field management, becoming key building blocks for high-performance integrated optoelectronics and flat optics. However, direct optical inspection of integrated chips remains a missing metrology gap that hinders quick feedback between design and fabrications. Here, we demonstrate that photothermal nonlinear scattering microscopy can be used for direct imaging and resolving of integrated optoelectronic chips beyond the diffraction limit.
View Article and Find Full Text PDFSci Rep
January 2025
Institute for Functional Matter and Quantum Technologies, University of Stuttgart, 70569, Stuttgart, Germany.
Inverse design via topology optimization has led to innovations in integrated photonics and offers a promising way for designing high-efficiency on-chip couplers with a minimal footprint. In this work, we exploit topology optimization to design a compact vertical coupler incorporating a bottom reflector, which achieves sub-decibel coupling efficiency on the 220-nm silicon-on-insulator platform. The final design of the vertical coupler yields a predicted coupling efficiency of -0.
View Article and Find Full Text PDFWe present both experimental and simulation results for a fully etched, C-band GC fabricated in an 800 nm silicon nitride platform that significantly reduces backreflections. They are minimized by truncating the initial grates, which deflect reflected light at an oblique angle and excite higher-order modes in the tapered waveguide that is filtered out. Insertion losses resulting from this modification of the grating coupler are mitigated by an adaptive redesign of the grates that corrects incurred errors in the generated phase front.
View Article and Find Full Text PDFNanoscale Adv
January 2025
School of Electrical Engineering and Computer Science, University of Ottawa Ottawa Ontario K1N 6N5 Canada
Interference of surface plasmons has been widely utilized in optical metrology for applications such as high-precision sensing. In this paper, we introduce a surface plasmon interferometer with the potential to be arranged in arrays for parallel multiplexing applications. The interferometer features two grating couplers that excite surface plasmon polariton (SPP) waves traveling along a gold-air interface before converging at a gold nanoslit where they interfere.
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