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Metal gratings for in-coupling a Gaussian beam incident from broadside to the long-range surface plasmon polariton (LRSPP) propagating in one direction along a membrane-supported Au slab bounded by air or water are proposed and modeled by the finite-difference time-domain method. Grating couplers for out-coupling the propagating LRSPP into free radiation directed along broadside are also investigated. Short grating designs consisting of a small number of Au bumps yield 15% to 20% in-coupling efficiencies, and about 60% out-coupling efficiencies. LRSPP back-reflections along the membrane waveguide caused by the out-coupling grating are also calculated and discussed.
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http://dx.doi.org/10.1364/OE.18.008006 | DOI Listing |
Photonic crystal nanobeam gratings (PCNGs) enable broad-band and flat-top reflection responses within short grating lengths due to their large coupling coefficients. In this Letter, we propose and experimentally demonstrate a channel-drop filter (CDF) based on a dual-waveguide apodized PCNG. The dual-waveguide structure realizes the decoupling of grating apodization from mode conversion.
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March 2025
A compact and scalable mode (de)multiplexer stands as a pivotal component in on-chip mode division multiplexing systems. Subwavelength gratings can flexibly adjust the waveguide refractive index at the subwavelength scale, while inverse design emerges as a promising methodology for optimizing extensive and intricate parameter sets. Here we propose and experimentally demonstrate a compact mode (de)multiplexer using inverse-designed subwavelength grating structures.
View Article and Find Full Text PDFGrating couplers typically encounter minimum feature size (MFS) constraints in fabrication. To address this issue, we incorporated user-defined apodization profiles into the inverse design process to enhance conversion efficiency (CE). We optimized grating parameters based on lithium-niobate on insulator (LNOI) platforms.
View Article and Find Full Text PDFThis study introduces a hybrid, integrated two-dimensional multi-layer optical phased array architecture that is characterized by its compactness, low loss, high performance, and versatility. It is suitable for applications ranging from space communication to sensor integration. We have delineated the essential requirements for cost-effective, miniaturized, and widely applicable heterostructure silicon photonics and highlighted the benefits of this architectural approach.
View Article and Find Full Text PDFHigh-performance polarization beam splitters (PBSs) are essential for maintaining signal integrity and minimizing interference in advanced photonic applications. This paper experimentally demonstrates a high-performance, ultra-broadband on-chip silicon PBS that integrates a mode conversion Bragg grating (MC-BG) with an adiabatic asymmetric directional coupler (ADC). The MC-BG is implemented by etching a hole-structured grating array into a multimode waveguide, serving as a polarization-dependent broadband mode router.
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