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Sampled-Data Adaptive ESO Based Composite Control for Nano-Positioning Systems
摘要： In this paper, we demonstrate ultra-fast millimeter wave beam steering with settling times below 50 ps. A phased array antenna with two elements is employed to realize beam steering. The phased array feeder is implemented with a recently introduced time delay line that provides, at the same time, an ultra-fast tunability, broadband operation, and continuous tuning. Our implementation is used to perform symbol-by-symbol steering. In our demonstration, the beam direction is switched between two sequentially transmitted symbols toward two receivers placed 30° apart. We show the successful symbol-by-symbol steering for data streams as fast as 10 GBd. The suggested scheme shows that the ultra-fast beam steering is becoming practical and might ultimately enable novel high bit-rate multiple access schemes.
关键词： microwave photonics,millimeter wave communication,Ultra-fast beam steering,radio access network
更新于2025-09-23 15:19:57
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Recent progress in epitaxial growth of III–V quantum-dot lasers on silicon substrate
摘要： In the past few decades, numerous high-performance silicon (Si) photonic devices have been demonstrated. Si, as a photonic platform, has received renewed interest in recent years. Efficient Si-based III–V quantum-dot (QDs) lasers have long been a goal for semiconductor scientists because of the incomparable optical properties of III–V compounds. Although the material dissimilarity between III–V material and Si hindered the development of monolithic integrations for over 30 years, considerable breakthroughs happened in the 2000s. In this paper, we review recent progress in the epitaxial growth of various III–V QD lasers on both offcut Si substrate and on-axis Si (001) substrate. In addition, the fundamental challenges in monolithic growth will be explained together with the superior characteristics of QDs.
关键词： quantum dots,silicon photonics,semiconductor laser,epitaxial growth
更新于2025-09-23 15:19:57
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Recent advances of heterogeneously integrated III–V laser on Si
摘要： Due to the indirect bandgap nature, the widely used silicon CMOS is very inefficient at light emitting. The integration of silicon lasers is deemed as the ‘Mount Everest’ for the full take-up of Si photonics. The major challenge has been the materials dissimilarity caused impaired device performance. We present a brief overview of the recent advances of integrated III–V laser on Si. We will then focus on the heterogeneous direct/adhesive bonding enabling methods and associated light coupling structures. A selected review of recent representative novel heterogeneously integrated Si lasers for emerging applications like spectroscopy, sensing, metrology and microwave photonics will be presented, including DFB laser array, ultra-dense comb lasers and nanolasers. Finally, the challenges and opportunities of heterogeneous integration approach are discussed.
关键词： silicon photonics,heterogeneous integration,integrated circuits,lasers
更新于2025-09-23 15:19:57
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III–V compound materials and lasers on silicon
摘要： Silicon-based photonic integration has attracted the interest of semiconductor scientists because it has high luminous efficiency and electron mobility. Breakthroughs have been made in silicon-based integrated lasers over the past few decades. Here we review three main methods of integration of III–V materials on Si, namely direct growth, bonding, and selective-area hetero-epitaxy. The III–V materials we introduced mainly include materials such as GaAs and InP. The lasers are mainly lasers of related communication bands. We also introduced the advantages and challenges of the three methods.
关键词： integrated photonics,hybrid laser,silicon
更新于2025-09-23 15:19:57
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Compact and Fabrication-Tolerant Waveguide Bends Based on Quadratic Reflectors
摘要： We propose and experimentally demonstrate a broadband, polarization-diverse compact bending design for low-index-contrast waveguides, where light is re-directed via total internal reflection (TIR) on an air-trench quadratic (elliptical or parabolic) reflector surface. Compared to prior work based on flat TIR mirrors, the quadratic reflector design contributes to minimized mode leakage and reduced optical losses, enabling high-density, scalable photonic architectures at the chip and board levels. Moreover, we develop a self-aligned fabrication process where the reflector and the waveguide segments are defined in a single lithography step, thereby circumventing the alignment sensitivity issue common to traditional air trench structures. Our simulations predict bending losses down to < 0.14 dB per 90° and 180° bend at 850 nm wavelength, and we experimentally measure broadband losses of ~ 0.3 dB per 90° and 180° bend for both TE and TM polarizations in structures fabricated using standard UV lithography.
关键词： polymer waveguide,free-form reflector,integrated photonics,waveguide bend,waveguide
更新于2025-09-23 15:19:57
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[IEEE 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Daejeon, Korea (South) (2019.7.28-2019.8.1)] 2019 International Conference on Optical MEMS and Nanophotonics (OMN) - Fast switching via frustrated total internal reflection in silicon photonics MEMS-actuated waveguides
摘要： We present a switching concept based on total internal reflection (TIR) and frustrated-TIR (F-TIR) using a MEMS movable waveguide fully compatible with silicon photonics technology. The switching element allows implementing large-scale photonic switches.
关键词： MEMS switch,silicon photonics,Optical Switching,data center networking
更新于2025-09-23 15:19:57
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Femtosecond laser additive and subtractive micro-processing: enabling a high-channel-density silica interposer for multicore fibre to silicon-photonic packaging
摘要： Great strides have been made over the past decade to establish femtosecond lasers in advanced manufacturing systems for enabling new forms of non-contact processing of transparent materials. Research advances have shown that a myriad of additive and subtractive techniques is now possible for flexible 2D and 3D structuring of such materials with micro- and nano-scale precision. In this paper, these techniques have been refined and scaled up to demonstrate the potential for 3D writing of high-density optical packaging components, specifically addressing the major bottleneck for efficiently connecting optical fibres to silicon photonic (SiP) processors for use in telecom and data centres. An 84-channel fused silica interposer was introduced for high-density edge coupling of multicore fibres (MCFs) to a SiP chip. Femtosecond laser irradiation followed by chemical etching (FLICE) was further harnessed to open alignment sockets, permitting rapid assembly with precise locking of MCF positions for efficient coupling to laser written optical waveguides in the interposer. A 3D waveguide fanout design provided an attractive balancing of low losses, mode-matching, high channel density, compact footprint, and low crosstalk. The 3D additive and subtractive processes thus demonstrated the potential for higher scale integration and rapid photonic assembly and packaging of micro-optic components for telecom interconnects, with possible broader applications in integrated biophotonic chips or micro-displays.
关键词： multicore fibre,waveguide fanout,silicon photonics interposer,space-division multiplexing,fibre socket,femtosecond laser micro-processing,photonic packaging
更新于2025-09-23 15:19:57
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Compact Graphene Plasmonic Slot Photodetector on Silicon-on-insulator with High Responsivity
摘要： Graphene has extraordinary electro-optic properties and is therefore a promising candidate for monolithic photonic devices such as photodetectors. However, the integration of this atom-thin layer material with bulky photonic components usually results in a weak light-graphene interaction leading to large device lengths, limiting electro-optic performance. In contrast, here we demonstrate a plasmonic slot graphene photodetector on silicon-on-insulator platform with high responsivity of 0.7 A/W given a just 5 μm-short device length. We observe that the maximum photocurrent, and hence the highest responsivity, scales inversely with the slot width. Using a dual-lithography step, we realize 15 nm narrow slots that show a 30-times higher responsivity per unit device-length compared to photonic graphene photodetectors. Furthermore, we reveal that the back-gated electrostatics is overshadowed by channel-doping contributions induced by the contacts of this ultra-short channel graphene photodetector. This leads to quasi charge neutrality, which explains both the previously-unseen offset between the maximum photovoltaic-based photocurrent relative to graphene’s Dirac point and the observed non-ambipolar transport. Such micrometer compact and absorption-efficient photodetectors allow for short-carrier pathways in next-generation photonic components, while being an ideal testbed to study short-channel carrier physics in graphene optoelectronics.
关键词： plasmonics,photovoltaic effect,graphene,photodetector,bolometric effect,Silicon photonics
更新于2025-09-23 15:19:57
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Metasurfaces: Subwavelength nanostructure arrays for ultrathin flat optics and photonics
摘要： Miniaturization is a strong demand of modern scientific technology. However, conventional optical components based on refraction suffer from functional degradation as the device size decreases. Metasurfaces consisting of subwavelength optical antenna arrays have emerged as planar optical devices that enable many promising applications in lenses, holograms, and optical cloaks. During recent decades, metasurfaces have been developed for their specific functionalities by exploiting new materials and design algorithms. In this issue of MRS Bulletin, progress in metasurfaces is discussed to provide a comprehensive understanding of metasurfaces and their novel applications in optics and photonics.
关键词： subwavelength nanostructure arrays,photonics,Metasurfaces,ultrathin flat optics
更新于2025-09-23 15:19:57
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Realization of high-quality InGaAs/GaAs quantum dot growth on Ge substrate and improvement of optical property through ex-situ ion implantation
摘要： Epitaxial growth of III-V heterostructures on non-native substrates such as Silicon (Si) or Germanium (Ge) is one of the promising research topics for the last two decades. The interface between polar III-V semiconductors and non-polar substrates (Si or Ge) plays a crucial role in monolithic integration. However, there is an anticipation of epitaxial GaAs growth on Ge substrate because of the lower mismatch of lattice constants and thermal expansion coefficients between them. Therefore, the high-quality growth of III-V semiconductor heterostructures on Ge substrates would overcome the impediment to Si-photonics, where the monolithic integration of optoelectronic device structures can be done using a Ge graded layer on Si. Here, we have explored the epitaxial growth of multi-layer InGaAs/GaAs quantum dot heterostructures on Ge substrates and compared the optical and structural properties with the QDs grown on GaAs substrate. The optical properties of all samples are investigated with the help of photoluminescence (PL) and time-resolved photoluminescence (TRPL), whereas the morphology of the QDs is observed through cross-sectional transmission electron microscopy (XTEM) images. An enhancement in the optical characteristics (PL peak wavelength, activation energy, carrier lifetime) is found for the QDs grown on Ge substrate with the super-lattice buffer (SLB) layer. The minimization of defects and dislocations in the heterostructure is also realized for the structure with the SLB layer. Furthermore, a two-fold enhancement in PL intensity and 24 meV increment in activation energy is achieved through ex-situ H ion-implantation, which approached the values obtained for the QD heterostructure grown on GaAs substrate.
关键词： Photoluminescence,Molecular beam epitaxy,Time-resolved photoluminescence,Silicon photonics,Quantum dots,Ion implantation
更新于2025-09-23 15:19:57