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All-Dielectric Nanoresonators for ??(2) Nonlinear Optics
摘要： Metal-less nanophotonics offers new opportunities for non-linear optics with respect to optical waveguides and microresonators, taking advantage of the progress within nanofabrication to boost the development of subwavelength Mie-type structures. Here, we review recent results on second harmonic generation with semiconductor nanoresonators, focusing on their scattering features in terms of efficiency and control over radiation patterns. First, two theoretical models are comparatively discussed with a view to possible improvements in analysis and design. Then, some relevant experiments are reported, and the origin of the χ(2) generation is discussed, outlining the main open topics to investigate in the near future and the advantages offered by these nanostructures to the development of novel photonic devices.
关键词： Mie resonances,second harmonic generation,AlGaAs nanoresonators,all-dielectric resonators,nanophotonics
更新于2025-09-19 17:13:59
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Surface Polariton‐Like s‐Polarized Waveguide Modes in Switchable Dielectric Thin Films on Polar Crystals
摘要： Surface phonon polaritons (SPhPs) and surface plasmon polaritons (SPPs), evanescent modes supported by media with negative permittivity, are a fundamental building block of nanophotonics. These modes are unmatched in terms of field enhancement and spatial confinement, and dynamical all-optical control can be achieved, e.g., by employing phase-change materials. However, the excitation of surface polaritons in planar structures is intrinsically limited to p-polarization. On the contrary, waveguide modes in high-permittivity films can couple to both p- and s-polarized light, and in thin films, their confinement can become comparable to surface polaritons. Here, it is demonstrated that the s-polarized waveguide mode in a thin Ge3Sb2Te6 (GST) film features a similar dispersion, confinement, and electric field enhancement as the SPhP mode of the silicon carbide (SiC) substrate, while even expanding the allowed frequency range. Moreover, it is experimentally shown that switching the GST film grants nonvolatile control over the SPhP and the waveguide mode dispersions. An analytical model is provided for the description of the GST/SiC waveguide mode and it is shown that the concept is applicable to the broad variety of polar crystals throughout the infrared spectral range. As such, complementarily to the polarization-limited surface polaritons, the s-polarized waveguide mode constitutes a promising additional building block for nanophotonic applications.
关键词： waveguide modes,infrared spectral range,phase-change materials,surface plasmon polaritons,silicon carbide,nanophotonics,Ge3Sb2Te6,surface phonon polaritons,s-polarized light
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Sub-Decibel Off-Chip Fiber Couplers Based on L-Shaped Waveguides and Subwavelength Grating Metamaterials
摘要： Uniform grating couplers based on versatile L-shaped waveguides are experimentally demonstrated, with coupling loss of -2.7 dB and back-reflections of -20 dB. Apodized couplers with subwavelength-grating metamaterials predict improved fiber-chip coupling down to -0.46 dB within device layouts compatible with lithographic technologies available in nanophotonic foundries.
关键词： silicon-on-insulator,sub-wavelength grating metamaterials,deep-ultraviolet technology,silicon nanophotonics,grating couplers,mass-scale production
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - High-Speed Germanium Pin Photodiodes Integrated on Silicon-on-Insulator Nanophotonic Waveguides
摘要： Hetero-structured silicon-germanium-silicon photodetectors operating under low-reverse-voltages with high responsivity, fast response, and low dark-current levels are reported. A bit-error-rate of 10-9 is experimentally achieved for conventional data rates of 10, 20, and 25 Gbps, providing optical power sensitivities of -13.9, -12.7, and -11.3 dBm.
关键词： silicon-on-insulator,complementary metal-oxide-semiconductor technology,silicon nanophotonics,germanium,optical photodetectors
更新于2025-09-16 10:30:52
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Ultra-narrow spectral response of a hybrid plasmonic-grating sensor
摘要： We configure and analyze a nanostructured device that hybridizes grating modes and surface plasmon resonances. The model uses an effective index of refraction that considers the volume fraction of the involved materials, and the propagation depth of the plasmon through the structure. Our geometry is an extruded low-order diffraction grating made of dielectric nano-triangles. Surface plasmon resonances are excited at a metal/dielectric interface, which is separated from the analyte by a high-index dielectric layer. The optical performance of the refractometric sensor is highly competitive in sensitivity and figure of merit (FOM) because of the the ultra-narrow spectral response (below 0.1 nm). Moreover, it is operative within a wide range of the index of refraction (from 1.3 till 1.56), and also works under normal incidence conditions.
关键词： plasmonics,nanophotonics,optical sensors
更新于2025-09-16 10:30:52
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[IEEE 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Munich, Germany (2019.6.23-2019.6.27)] 2019 Conference on Lasers and Electro-Optics Europe & European Quantum Electronics Conference (CLEO/Europe-EQEC) - Placing Quantum Dots in 3D Photonic Crystals and Finding Them Back
摘要： It is a major outstanding goal in Nanophotonics to precisely place quantum emitters inside a three-dimensional (3D) metamaterial. It is well-known that such control offers exquisite control over cavity QED, spontaneous and stimulated emission, and even non-linear optics. Theory predicts that the emission of an emitter, e.g. a quantum dot, varies spatially on 100s nm scale. Thus, the challenge is to place emitters with a precision better than Δx < 100 nm. We present our newly developed chemical toolbox to fix the positions of quantum dots with a polymer brush layer with thicknesses in the 10s nm range in silicon nanostructures. Once 3D positioning is successful, a second challenge arises, namely how to non-destructively find where the emitter sits in the 3D structure. Since nanophotonic materials are necessarily opaque, optical microscopy has insufficient penetration depth, apart from its limited resolution. While scanning electron microscopy (SEM) offers sufficient spatial resolution, it has a small penetration depth hence only the sample surface is viewed but not the bulk. X-ray techniques are promising tools, in view of excellent penetration depth, non-destructive character, and nm spatial resolution. Therefore, we study a 3D Si photonic band gap crystal with infiltrated PbS nanocrystal quantum dots by X-ray fluorescence tomography. Our photonic crystals have the inverse woodpile structure that exhibits a broad full and complete 3D band gap. The crystal are made by CMOS-compatible methods using deep reactive ion-etching through tailored masks. Fluorescence tomography was performed at the ESRF (beamline ID-16NI). X-rays (17 keV photon energy) are focussed in the sample. We collect data at 17 different angles while rotating the crystal from 0 to 180°. Projection maps are obtained at every angle, followed by standard tomographic reconstruction to obtain the 3D atom density distribution with 50 nm spatial 3D resolution for each chemical element. Fig. 1(B) shows a projection map of the number of lead atoms - from the quantum dots - in one crystal. The volume is a cube that contains the 3D photonic crystal structure that is surrounded by bulk silicon above and by the 2D array of deep pores that are etched first. Close inspection of the 3D volume after reconstruction indeed reveals two sets of pores running in the Z and the X-directions, matching the design (Fig. 1(A). The structure is periodic with lattice parameters that also match the design very well. It appears that the quantum dots are located throughout the whole crystal volume. Their position correlates well with elements characteristic of the polymer brush layer. Finally, we find that after the X-ray experiment the quantum dots remain optically active. We conclude that 3D X-ray fluorescence tomography has great potential to solve many future questions on 3D optical metamaterials for nanophotonic research and applications, including cavity arrays, physically unclonable functions, and precise localization of light emitters as qubits and for enhanced lighting efficiency.
关键词： nanophotonics,polymer brush layer,quantum dots,3D photonic crystals,X-ray fluorescence tomography
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Singapore, Singapore (2019.8.28-2019.8.30)] 2019 IEEE 16th International Conference on Group IV Photonics (GFP) - Sub-Decibel Off-Chip Fiber Couplers Based on Z-Shaped Waveguides and Subwavelength Grating Metamaterials
摘要： Uniform grating couplers based on versatile L-shaped waveguides are experimentally demonstrated, with coupling loss of -2.7 dB and back-reflections of -20 dB. Apodized couplers with subwavelength-grating metamaterials predict improved fiber-chip coupling down to -0.46 dB within device layouts compatible with lithographic technologies available in nanophotonic foundries.
关键词： deep-ultraviolet technology,mass-scale production,sub-wavelength grating metamaterials,silicon-on-insulator,silicon nanophotonics,grating couplers
更新于2025-09-16 10:30:52
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[IEEE 2019 IEEE 14th International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Bangkok, Thailand (2019.4.11-2019.4.14)] 2019 IEEE 14th International Conference on Nano/Micro Engineered and Molecular Systems (NEMS) - Isotropic Nanophotonic Modulation with Hybrid Configuration for Surface Plasmon Resonance Application
摘要： This paper reports a novel method to modulate the surface plasmon resonance (SPR) by isotropically straining a polymeric substrate to induce reconfigurations of photonic nanostructures above the substrate. By macroscopic straining the substrate, the microscopic stress was transferred to the metallic nanostructures, which in turn induced different SPRs, as the operating principle. Studies indicated that although the substrate was anisotropically strained in limited directions, the SPR was modulated isotropically at the geometric center of the substrate. Demonstrative isotropic SPR modulation was achieved with a single and fundamental configuration of the nanostructures for the first time, and the tunable operation was proven by a color switched from blue to green. Comprehensive theoretical optical and mechanical designs, numerical mechanical evaluations, device fabrication, experimental verification, and analysis were conducted in this work.
关键词： nanophotonics,strain,color filter,surface plasmon resonance
更新于2025-09-16 10:30:52
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Introducing Waveguide Loss: Another Way to Realize a High-Sensitivity Microring Biosensor
摘要： Real-time and high-sensitivity biosensors are urgently needed in biochemistry. As one of the candidates, silicon-on-insulator (SOI) sensors exhibits excellent performances. However, there are still some limitations to hinder them to be applied to much wider scenarios. Fabrication tolerance is also required for the generalization of these micro- or nano-structure. In this work, we demonstrate an SOI waveguide biosensor for biochemical sensing with high sensitivity of 1.88×105 dB/RIU. Because of the compact structure and low demand for accuracy of fabrication, this device possesses better applicability and reliability.
关键词： Nanophotonics,Biosensor,SOI,Microring
更新于2025-09-16 10:30:52
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Solid-Electrolyte-Gated Graphene-Covered Metal-Insulator-Silicon-Insulator-Metal Waveguide With a Remarkably Large Modulation Depth
摘要： Silicon photonic modulators are an essential element in providing fast and massive connectivity to the data-centric world. Ever-increasing data usage requires them to be smaller, faster, and easier to fabricate. Graphene with exceptional properties has been emerging as a material for such next-generation silicon photonic modulators, and a variety of graphene-based photonic or plasmonic modulators have been realized and verified. However, due to weak light-graphene interaction in them, they have a modulation depth smaller than 0.16 dB/μm, which is similar to those of existing germanium-silicon electroabsorption modulators. This work reports a graphene-covered hybrid plasmonic waveguide that has truly strong light-graphene interaction. The hybrid plasmonic waveguide is realized with standard CMOS technology and efficiently coupled to a conventional Si waveguide. To prove the strong light-graphene interaction, solid-electrolyte gating is used to modulate the intensity of the waveguide although its modulation speed is slow. It is demonstrated that the waveguide has a remarkably large modulation depth of 0.276 dB/μm even though just one single-layer graphene covers the waveguide. This demonstration opens the door to the waveguide covered with a graphene-oxide-graphene capacitor, which may have a larger modulation depth and a large 3-dB bandwidth, and it is theoretically analyzed. This work may be the solid base for a graphene-based silicon photonic modulator which is theoretically expected to surpass current silicon photonic modulators.
关键词： intensity modulation,nanophotonics,optical waveguides,silicon photonics,Integrated optics
更新于2025-09-16 10:30:52