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- 摘要
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- 实验方案
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Arrays of Plasmonic Nanoparticle Dimers with Defined Nanogap Spacers
摘要： Plasmonic molecules are building blocks of metallic nanostructures that give rise to intriguing optical phenomena with similarities to those seen in molecular systems. The ability to design plasmonic hybrid structures and molecules with nanometric resolution would enable applications in optical metamaterials and sensing that presently cannot be demonstrated, because of a lack of suitable fabrication methods allowing the structural control of the plasmonic atoms on a large scale. Here we demonstrate a wafer-scale ‘lithography-free’ parallel fabrication scheme to realize nanogap plasmonic meta-molecules with precise control over their size, shape, material, and orientation. We demonstrate how we can tune the corresponding coupled resonances through the entire visible spectrum. Our fabrication method, based on glancing angle physical vapor deposition with gradient shadowing, permits critical parameters to be varied across the wafer and thus is ideally suited to screen potential structures. We obtain billions of aligned dimer structures with controlled variation of the spectral properties across the wafer. We spectroscopically map the plasmonic resonances of gold dimer structures and show that they are not only in a good agreement with numerically modeled spectra, but also remain functional, at least for a year, in an ambient condition.
关键词： glancing angle deposition,wafer-scale nanofabrication,asymmetric shadow,nanophotonics,optical metamaterials,scalable plasmonics
更新于2025-09-12 10:27:22
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Characterization of Waveguide Photonic Crystal Reflectors on Indium Phosphide Membranes
摘要： We present waveguide photonic crystal re?ectors on the InP-membrane-on-silicon (IMOS) platform, and a method to accurately measure the re?ectivity of those re?ectors. The photonic crystal holes are patterned on a waveguide using electron-beam lithography and etched through the waveguiding layer to create a broadband distributed Bragg re?ector. We show simulations of these re?ectors and experimental results of fabricated devices, both showing a high, free-to-choose re?ectivity, and high quality factor Fabry-P′erot cavities. We experimentally show re?ectivities higher than 95% for the re?ectors and a quality factor as high as 15,911±511 for a Fabry-P′erot cavity, using re?ectors with a length of only 4 microns. For the ?rst time, to our knowledge, two methods for measuring the re?ectivity are used for characterization of on-chip re?ectors to accurately determine the re?ection. The ?rst method is based on analysis of the transmission through a Fabry-P′erot cavity, the second is based on a direct four-port measurement of the re?ector. A systematic error is made in both methods, resulting in an upper and lower boundary for the actual re?ection coef?cient.
关键词： photonic crystals,nanophotonics,Photonic integrated circuits
更新于2025-09-12 10:27:22
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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) - Optical Resonances in a 3D Superlattice of Photonic Band Gap Cavities
摘要： The confinement of light in three dimensions (3D) is an active research topic in Nanophotonics, since it allows for ultimate control over photons [1]. A powerful tool to this end is a 3D photonic band gap crystal with a tailored defect that acts as a cavity or even a waveguide [2]. When a one-dimensional array of cavities is coupled, an intricate waveguiding system appears, known as a CROW (coupled resonator optical waveguide) [3]. Remarkably, 3D superlattices of coupled cavities that resonate inside a 3D band gap have not been studied to date. Recently, theoretical work has predicted the occurrence of “Cartesian light”, wherein light propagates by hopping only in high symmetry directions in space [4]. This represents the optical analog of the Anderson model for spins or electrons that is relevant for neuromorphic computing and may lead to intricate lasing [5]. To experimentally study the propagation of light in a 3D superlattice of band gap cavities, we have fabricated 3D nanostructures from silicon by reactive ion etching (see Fig. 1). The photonic crystal has the cubic diamond-like inverse woodpile structure that is composed of two perpendicular sets of pores (in the X and Z directions) [6] and that reveals a broad 3D photonic band gap. By intentionally making two proximal perpendicular pores smaller, light is confined at their intersection, thus forming a cavity [7]. By fabricating two arrays of defect pores (see Fig. 1) we realize a 3D cavity superlattice. The challenge we address here is to experimentally identify resonances in this complex system. We measure reflectivity of the crystals with a large aperture (NA = 0.85) for both s and p-polarizations. With our setup we also record lateral scattered light, i.e., light that is input in the Z-direction, scattered, and detected in the X-direction. In presence of the intentional defects, we observe troughs in the stop band in reflectivity. The corresponding lateral scattering spectrum shows peaks in the stopband at the same frequencies as the reflectivity troughs, see Fig. 2. To distinguish cavity resonances from random speckle, we record several spectra at different locations on the crystal. Peaks reproducing at the same frequencies are attributed to light scattered from the cavity resonances. The appearance of the scattering peaks strongly depends on polarization in conformity with numerical calculations [7]. We now extend the numerical work to the range of pore sizes probed experimentally.
关键词： nanophotonics,Cartesian light,3D photonic band gap,cavity superlattice,coupled resonator optical waveguide
更新于2025-09-12 10:27:22
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Silicon Non-Blocking 4 × 4 Optical Switch Chip Integrated With Both Thermal and Electro-Optic Tuners
摘要： We experimentally demonstrate an integrated strictly non-blocking silicon 4×4 optical switch chip that can be operated in both thermo-optic (TO) and electro-optic (EO) switching modes. It is based on the double-layer network (DLN) architecture and consists of twelve 2×2 Mach-Zehnder interferometer (MZI) switch elements. TO phase shifters based on TiN microheaters and EO phase shifters based on p-i-n diodes are embedded in both waveguide arms of the MZI elements. The power consumption for TO and EO switching is 34 mW/π and 7 mW/π, respectively. The on-chip insertion losses are 1.74 ± 0.59 dB and 3.79 dB ± 1.32 dB for TO and EO switching, respectively. Due to the merits of the DLN architecture and the optimized performance of the switch elements, the chip possesses low crosstalk of -29.1 dB and -19.4 dB for TO and EO switching, respectively. Quadrature phase-shift keying (QPSK) optical signals with a data rate of 64 Gb/s are transmitted through the switch with no observable deteriorations. Such an optical switch is a promising candidate for both optical circuit switching and optical packet switching for a variety of applications.
关键词： integrated nanophotonic systems,waveguide devices,Silicon nanophotonics
更新于2025-09-11 14:15:04
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MEMS-enabled Silicon Photonic Integrated Devices and Circuits
摘要： Photonic integrated circuits have seen a dramatic increase in complexity over the past decades. This development has been spurred by recent applications in datacenter communications and enabled by the availability of standardized mature technology platforms. Mechanical movement of wave-guiding structures at the micro- and nanoscale provides unique opportunities to further enhance functionality and to reduce power consumption in photonic integrated circuits. We here demonstrate integration of MEMS-enabled components in a simplified silicon photonics process based on IMEC’s Standard iSiPP50G Silicon Photonics Platform and a custom release process.
关键词： Microelectromechanical Systems,Photonic Integrated Circuits,Nanophotonics,Integrated Optics,Silicon Photonics
更新于2025-09-11 14:15:04
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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) - Strong Enhancement of Light Extraction Efficiency in Sub-Wavelength AlGaAs/GaAs Vertical-Emitting Nanopillars
摘要： Scaling down active nanophotonic devices, namely nano-lasers and nano-light-emitting diodes (nanoLEDs), to deep sub-micrometer sizes, is crucial to achieve small footprint (<1 μm2), low energy consumption (<10 fJ/bit), and efficient (>10%) light sources, as needed for future compact photonic integrated circuits for optical communications [1], and biosensing and bioimaging applications [2]. As the surface-to-volume ratio of these nanoscale sources increases substantially, among the numerous challenges, strong non-radiative processes and difficulties in extracting the light have been shown to have a detrimental effect on the external quantum efficiencies of nanoLEDs and nanolasers [3]. Although there has been intense research, particularly in light-enhancement and out-coupling methods, using for example 2D photonic crystals [4], optical nanoantennas [5], or nanowaveguides integrated with grating couplers [3], these approaches are extremely challenging to implement when the size of the light-emitting structures is drastically reduced to the deep-subwavelength (<<λ/3) scale. In this work, we report a strong enhanced signal at λ~670 nm in vertical-emitting undoped AlGaAs/GaAs/AlGaAs tapered pillars in a GaAs substrate, Fig. 1(a), when the emitting nominal area is decreased to the sub-μm scale. Vertical-emitting pillars ranging from 200 nm to 8 μm lateral width were fabricated using e-beam lithography and dry etching techniques and characterized using a micro-photoluminescence (PL) microscope with λ=561 nm laser excitation. Figure 1(b) shows examples of emission images for both optically pumped micropillars (top) and nanopillars (bottom) (the respective intensity profiles are shown inset). For the case of micropillars, clearly the light emission is reduced as the diameter decreases following a typical scaling law, d 2, of planar LEDs. However, as d is reduced from 4 μm to 0.2 μm sizes, particularly in the range of 300 nm < d < 400 nm, although the nominal emission area is reduced by a factor of more than 100, the intensity is reduced only by ~10 times. For example, the emitting intensity peaks for pillars with d=360 nm, and the integrated intensity is comparable to pillars with d~1 μm sizes. This strongly deviates from the d 2 dependence observed for micropillars, resulting in a 27-fold enhancement of emission. This striking effect is summarized in Fig. 1(c). Our FDTD simulations for a tapered d=360 nm nanopillar, Fig. 1(a)(bottom), indicate this enhancement is a result of a 3-fold effect: i) suppression of optical modes due to lateral size reduction, ii) efficient out-coupling to air, and iii) more directed emission of tapered pillars. Notably, as shown in the blue circles of Fig. 1(c), the emission can be further improved after surface passivation with (NH4)2S and dielectric capping with a ~50 nm SiO2 layer. For the case of sub-μm pillars, a 3-fold improvement of light emission is achieved as compared with unpassivated samples. In summary, a large improvement of light-extraction in sub-λ vertical-emitting nanopillars is achieved. This pronounced effect enables bright emission in nanoscale devices comparable to the performance of μm-sized devices. This result, combined with the suppression of surface recombination, is crucial for the future development of high-performance nanoscale optoelectronic devices for low-power optical interconnects, supporting the realization of room-temperature highly efficient light sources in photonic integrated circuits.
关键词： sub-wavelength,nanophotonics,vertical-emitting nanopillars,AlGaAs/GaAs,light extraction efficiency
更新于2025-09-11 14:15:04
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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) - All-Dielectric High-Q Metasurfaces for Infrared Absorption Spectroscopy Applications
摘要： The mid-infrared (mid-IR) spectral range is crucial for spectroscopic investigations of biological systems since it contains the characteristic absorption signatures (i.e., the molecular ‘fingerprints’) of chemical and biological analytes, which are uniquely determined by the vibrational modes and associated absorption bands of its chemical bonds. Here we present a novel nanophotonics-based approach for detecting molecular fingerprints, which utilizes imaging-based methods to provide spectrometer-less operation in a miniaturized sensor device ideally suited for analyzing complex biological systems. The central building block of this technique is a pixelated dielectric metasurface where the individual metapixels are engineered to provide sharp resonances at a given resonance frequency. Each metapixel is made out of specifically designed zig-zag resonator arrays, which employ the concept of bound states in continuum to create high-Q resonances. The detection performance of the experimentally realized metasurface sensor was demonstrated by interrogating a monolayer of recombinant protein A/G molecules, which reveals the characteristic amide I and amide II absorption bands as distinct regions with attenuated peak reflectance of the resonances. A comparison of the total reflectance signals of all the metapixels before and after material adsorption delivers a distinct barcode pattern which can be used for chemically specific molecule detection. Importantly, this molecular barcoding method operates under broadband illumination and detection conditions, meaning that the chemically specific signals can be obtained without the need for spectrometry.
关键词： high-Q resonances,dielectric metasurface,nanophotonics,molecular barcoding,mid-infrared,molecular fingerprints
更新于2025-09-11 14:15:04
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Steering Second Harmonic Beam in Nanophotonic Waveguides by Gratings
摘要： Efficient manipulation of the wavefront at the nanoscale is important for optical beaming, signal encoding, and nonlinear phase matching, etc. Diffraction gratings are widely adapted for the control of the wavefront of lightwaves, but predominantly in linear optics. Here, we demonstrated the flexible steering of the second harmonic (SH) beams in nanophotonic waveguides using gratings. The emission angle of the SH signals can be shifted by an amount of 60° from the waveguide axis into the collection cone, allowing the detection of the otherwise undetectable SH from co-propagating waveguide modes in the high-loss waveguides. The SH conversion efficiency (3 × 10?5 W?1) from co-propagating modes contributes up to 26.7% of the total SH signal. As the pump wavelength varies from 770 to 840 nm, the SH beam is swept by up to 22°. This design functions as a nonlinear grating coupler for nanophotonic systems and could be used for efficient nonlinear coherent light generation and integrated nonlinear nanophotonics.
关键词： Fourier imaging,nanophotonics,second harmonic generation,nonlinear grating coupler,beam steering
更新于2025-09-11 14:15:04
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European Microscopy Congress 2016: Proceedings || Angle-resolved cathodoluminescence polarimetry on plasmonic nanostructures
摘要： Plasmonic metamaterials and metasurfaces have the ability to influence the propagation, confinement, and emission of light on a deep-subwavelength scale. Many of the optical properties of such materials are encoded in the spectrum, the angular intensity distribution, and the polarization of the far-field emission. Angle-resolved cathodoluminescence (CL) imaging spectroscopy (ARCIS) is a powerful platform for studying these properties, as it combines nanoscale excitation resolution, with the capability to measure both spectra and the angular emission intensity distribution. In particular, we use a 30 keV electron beam as a well-defined broad-band excitation source which is sensitive to the optical density of states. This method has been used to study the spectral and angular optical properties of a large variety of dielectric and plasmonic nanostructures. However, thus far we were only able to measure emission intensities and had to disregard the vectorial polarization nature of the light emission. The emission polarization contains valuable information, which can be used to identify multipoles, separate TM and TE modes in waveguides, characterize the coherence of an emission source etc. Here, we demonstrate a novel CL polarimetry technique in which we retrieve the Stokes vector, i.e. the full polarization state of the far-field emission, as function of angle [1]. To that end, we extend our setup to include a quarter-wave plate (QWP) and a linear polarizer in the beam path (see Figure 1 for a schematic representation of the setup). By taking six measurements with the appropriate combinations of QWP and polarizer angle we retrieve the polarization distribution in the detection plane. By applying a correction for the aluminum parabolic mirror optic we then find the emission polarization distribution. This approach is applied to gold plasmonic bull’s eye gratings which were fabricated using focused-ion-beam milling in a single-crystal gold substrate (see Figure 2(a) for an SEM image). These bull’s eyes can coherently couple out the Surface Plasmon Polaritons (SPPs) that are excited by the electron beam. Because the electron beam can be positioned at will, we can study the effect of exciting the bull’s eye at different positions. For central excitation, the grating is driven in phase leading to an azimuthally symmetric pattern and a radial polarization distribution, as expected from symmetry (see Figure 2(b-c)). However, when we excite off-center the patterns become significantly more complex, showing multiple lobes and alternating regions in angular space in which the polarization goes from circular to linear. To demonstrate the applicability to chiral structures, we move to spiral bull’s eyes with different handedness, and show that their chirality is reflected in the field distributions. The validity of the polarimetry technique is verified by measuring transition radiation which has a characteristic radial polarization distribution, similar to a vertical dipole source. This work paves the way for polarimetry measurements on a myriad of metallic and semiconductor nanophotonic geometries for characterization and better understanding of their optical properties.
关键词： Cathodoluminescence,plasmonics,polarization,nanophotonics
更新于2025-09-11 14:15:04
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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) - Anti-Stokes Cryoluminescence in Nanomaterials
摘要： Study of the electromagnetic fields interaction with structured nanomaterials with photonic band gaps is one of the most rapidly developing areas of nanophotonics. In modern optics, such nanomaterials are actively used to process the characteristics of electromagnetic radiation. Firstly, the properties of amplification of the local field are used, secondly, the properties of the photonic bandgap. A typical example of local field amplification is the work [1], in which the authors used a coating of submicron dielectric spheres on a copper target in order to achieve more than tenfold increasing the efficiency of X-ray generation. Using the properties of the photonic band gap leads to the increasing well-known nonlinear effects efficiency and to the appearance of new nonlinear phenomena. One of these phenomena is anti-Stokes cryoluminescence in nanomaterials - light emission at low temperature under laser action in the spectral range with higher frequency than that of exciting light. We observed bright and long (up to few seconds) emission in blue-green range under 20ns ruby laser pulses excitation in different nanomaterials at low temperatures [2-3]. One of the reasons of this effect is triboluminescence, free radicals appearing and structure defects forming, like in bulk materials [4]. In the present work we show that in nanomaterials of different nature there are two types of temporal dependence: short (few microseconds) and long (up to 10-12 seconds). Long dependence exists at temperatures lower than 110 K. Temporal dependence for anti-Stokes luminescence in synthetic opal matrices for temperatures lower and higher this threshold is shown in Figure 1.
关键词： anti-Stokes cryoluminescence,nanophotonics,electromagnetic radiation,photonic band gaps,nanomaterials
更新于2025-09-11 14:15:04