- 标题
- 摘要
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- 实验方案
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Twins in YAl3(BO3)4 and K2Al2B2O7 Crystals as Revealed by Changes in Optical Activity
摘要： Many borate crystals feature nonlinear optical properties that allow for efficient frequency conversion of common lasers down into the ultraviolet spectrum. Twinning may degrade crystal quality and affect nonlinear optical properties, in particular if crystals are composed of twin domains with opposing polarities. Here, we use measurements of optical activity to demonstrate the existence of inversion twins within single crystals of YAl3(BO3)4 (YAB) and K2Al2B2O7 (KABO). We determine the optical rotatory dispersion of YAB and KABO throughout the visible spectrum using a spectrophotometer with rotatable polarizers. Space-resolved measurements of the optical rotation can be related to the twin structure and give estimates on the extent of twinning. The reported dispersion relations for the rotatory power of YAB and KABO may be used to assess crystal quality and to select twin-free specimens.
关键词： optical activity,inversion twin,YAB,optical rotatory dispersion,KABO,second harmonic generation,frequency conversion,K2Al2B2O7,NLO crystals,YAl3(BO3)4
更新于2025-10-22 19:40:53
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[IEEE 2018 China International SAR Symposium (CISS) - Shanghai (2018.10.10-2018.10.12)] 2018 China International SAR Symposium (CISS) - Design of a X -band Frequency-Conversion Front-End T/R Module
摘要： In the microwave system, the performance of the up-converter and the down-converter play a key role in the whole system. The theory and design of the X-band up-down frequency converter are researched in this thesis. The major job in this thesis is to design and manufacture a microwave up-convert system and a down-convert system to realize the frequency conversion performance. The up-convert system can convert the signal from the UHF-band to the X-band, and then the output power up to 20 watts. In the same way, the down-convert system can convert the signal from the X-band to the UHF-band. According to the technical requirements, we do the schematic design, the feasibility analysis and the unit circuit’s index estimation respectively, and achieve the circuit design by using a variety of computer-aided software. Finally we have completed the assembly, debugging and testing of the systems. All above achieve the purpose that the theoretical research and engineering application are combined by each other. The kinds Of unit circuit used in the microwave conversion components include the filter, frequency conversion and amplification circuit (the selected MMIC of amplifier, mixer, switch), power circuit and digital logic circuit. The measurement results of the Frequency-conversion front-end TR module have a good agreement with the simulation results. The up-converter system achieved output power better than 43dBm and spurs rejection better than 50dBc. The down-convert system achieved noise figure less than 3dB noise figure and conversion gain bigger than 55dB.
关键词： Frequency-Conversion,spurs rejection,mixer,conversion gain
更新于2025-09-23 15:22:29
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Nonlinear optics with resonant metasurfaces
摘要： The field of nonlinear optics is a well-established discipline that relies on macroscopic media and employs propagation distances longer than a wavelength of light. Recent progress with electromagnetic metamaterials has allowed for the expansion of this field into new directions of new phenomena and novel functionalities. In particular, nonlinear effects in thin, artificially structured materials such as metasurfaces do not rely on phase-matching conditions and symmetry-related selection rules of natural materials; they may be substantially enhanced by strong local and collective resonances of fields inside the metasurface nanostructures. Consequently, nonlinear processes may extend beyond simple harmonic generation and spectral broadening due to electronic nonlinearities. This article provides a brief review of basic concepts and recent results in the field of nonlinear optical metasurfaces.
关键词： frequency conversion,high-harmonic generation,resonances,metasurfaces,nonlinear optics
更新于2025-09-23 15:19:57
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Active control of multiple, simultaneous nonlinear optical processes in plasmonic nanogap cavities
摘要： Plasmonic structures are promising to enhance and control nonlinear optical processes as the subwavelength-scale elements not only increase the local electric field intensities but also result in relaxed phase matching conditions. This opens the possibility to observe and further manipulate multiple nonlinear optical processes simultaneously which would be forbidden in bulk crystals due to incompatible phase matching requirements. Here we enhance and control the relative strength between third harmonic generation (THG), sum frequency generation (SFG) and four wave mixing (FWM) arising from 1-7 nm Al2O3 layers sandwiched between a gold film and silver nanorectangles. We demonstrate that the relative strength of the three, simultaneous nonlinear optical processes can be precisely controlled by either the ratio between the powers of the two excitations or the thickness of the Al2O3 layer. Furthermore, enhancements up to 106-fold for THG and FWM are observed along with 104-fold enhancements for SFG response when the resonance of the transverse and longitudinal mode of the cavity are matched to the two pump excitations. The ability to obtain and control multiple, nonlinear optical processes simultaneously opens new capabilities for advanced on-chip manipulation and processing of optical signals on the deep nanoscale.
关键词： metasurface,frequency conversion,plasmonics,tuning,nonlinear optics
更新于2025-09-23 15:19:57
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[IEEE 2019 Compound Semiconductor Week (CSW) - Nara, Japan (2019.5.19-2019.5.23)] 2019 Compound Semiconductor Week (CSW) - Nanoscale Transfer Printing for the Heterogeneous Integration of Semiconductor Nanowire Lasers
摘要： InP-based high electron mobility transistors (InP-HEMTs) and graphene-channel FETs (G-FETs) are experimentally examined as photonic frequency converters for future broadband optical and wireless communication systems. Optoelectronic properties and three-terminal functionalities of the InP-HEMTs and G-FETs are exploited to perform single-chip photonic double-mixing operation over the 120 GHz wireless communication band. A 10 Gbit/s-class data signal on a 112.5 GHz carrier is mixed down to a 25 GHz IF band with an 87.5 GHz LO signal that is simultaneously self-generated from an optically injected photomixed beat note. The results suggest that the intrinsic channel of the G-FET can achieve a speed performance that is superior to that of an InP-HEMT having an equivalent device feature size. The reduction of the extrinsic parasitic resistances and the implementation of an efficient photo-absorption structure in the G-FET may allow a millimeter-wave and sub-THz photonic frequency conversion with a sufficiently high conversion gain for practical purposes.
关键词： millimeter wave photonics,frequency conversion,FETs,millimeter wave communication,InP,graphene,HEMTs,radio access networks
更新于2025-09-19 17:13:59
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Facile enhancement of optical sensitivity in GaN ultraviolet photodetectors by using in-situ plano-convex polymer lens
摘要： InP-based high electron mobility transistors (InP-HEMTs) and graphene-channel FETs (G-FETs) are experimentally examined as photonic frequency converters for future broadband optical and wireless communication systems. Optoelectronic properties and three-terminal functionalities of the InP-HEMTs and G-FETs are exploited to perform single-chip photonic double-mixing operation over the 120 GHz wireless communication band. A 10 Gbit/s-class data signal on a 112.5 GHz carrier is mixed down to a 25 GHz IF band with an 87.5 GHz LO signal that is simultaneously self-generated from an optically injected photomixed beat note. The results suggest that the intrinsic channel of the G-FET can achieve a speed performance that is superior to that of an InP-HEMT having an equivalent device feature size. The reduction of the extrinsic parasitic resistances and the implementation of an efficient photo-absorption structure in the G-FET may allow a millimeter-wave and sub-THz photonic frequency conversion with a sufficiently high conversion gain for practical purposes.
关键词： millimeter wave photonics,frequency conversion,FETs,millimeter wave communication,InP,graphene,HEMTs,radio access networks
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Solution-processed ultrathin SnO <sub/>2</sub> passivation of Absorber/Buffer Heterointerface and Grain Boundaries for High Efficiency Kesterite Cu <sub/>2</sub> ZnSnS <sub/>4</sub> Solar Cells
摘要： InP-based high electron mobility transistors (InP-HEMTs) and graphene-channel FETs (G-FETs) are experimentally examined as photonic frequency converters for future broadband optical and wireless communication systems. Optoelectronic properties and three-terminal functionalities of the InP-HEMTs and G-FETs are exploited to perform single-chip photonic double-mixing operation over the 120 GHz wireless communication band. A 10 Gbit/s-class data signal on a 112.5 GHz carrier is mixed down to a 25 GHz IF band with an 87.5 GHz LO signal that is simultaneously self-generated from an optically injected photomixed beat note. The results suggest that the intrinsic channel of the G-FET can achieve a speed performance that is superior to that of an InP-HEMT having an equivalent device feature size. The reduction of the extrinsic parasitic resistances and the implementation of an efficient photo-absorption structure in the G-FET may allow a millimeter-wave and sub-THz photonic frequency conversion with a sufficiently high conversion gain for practical purposes.
关键词： millimeter wave photonics,radio access networks,graphene,FETs,HEMTs,InP,millimeter wave communication,frequency conversion
更新于2025-09-19 17:13:59
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[IEEE 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Chicago, IL, USA (2019.6.16-2019.6.21)] 2019 IEEE 46th Photovoltaic Specialists Conference (PVSC) - Numerical modeling and experimental realization of wide bandgap ZnTe-based solar cells for semi-transparent PV application
摘要： InP-based high electron mobility transistors (InP-HEMTs) and graphene-channel FETs (G-FETs) are experimentally examined as photonic frequency converters for future broadband optical and wireless communication systems. Optoelectronic properties and three-terminal functionalities of the InP-HEMTs and G-FETs are exploited to perform single-chip photonic double-mixing operation over the 120 GHz wireless communication band. A 10 Gbit/s-class data signal on a 112.5 GHz carrier is mixed down to a 25 GHz IF band with an 87.5 GHz LO signal that is simultaneously self-generated from an optically injected photomixed beat note. The results suggest that the intrinsic channel of the G-FET can achieve a speed performance that is superior to that of an InP-HEMT having an equivalent device feature size. The reduction of the extrinsic parasitic resistances and the implementation of an efficient photo-absorption structure in the G-FET may allow a millimeter-wave and sub-THz photonic frequency conversion with a sufficiently high conversion gain for practical purposes.
关键词： millimeter wave photonics,radio access networks,graphene,FETs,HEMTs,InP,millimeter wave communication,frequency conversion
更新于2025-09-19 17:13:59
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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) - Quadratic Solitons and their Interaction with Dispersive Waves in Lithium Niobate Nano-Waveguides
摘要： Lithium Niobate (LN) nano-waveguides combine the high nonlinearity and broadband transparency of LN with the sensitive tunability of geometric group velocity dispersion (GVD) and the strong field enhancement of subwavelength waveguides. Together these properties make the newly emerging LN nano-waveguides a compelling candidate for research into dynamics of quadratic temporal solitons, and frequency conversion processes driven by solitons interacting with dispersive waves. Emission of resonant radiation (RR) by temporal solitons due to cubic nonlinearity is known to be one of the key mechanism behind supercontinuum generation. Recent research into cubic solitons interacting with quadratic nonlinearities has found new mechanisms for tunable RR. In this work we analyse theoretically bright temporal quadratic solitons in LN nano-waveguides. Quadratic solitons consist of two co-propagating pulses at fundamental harmonic (FH) and second harmonic (SH) frequencies. The interaction between these two pulses mediated by a nonlinear material allows for the self-phase modulation crucial for soliton formation. Using the slowly varying envelope approximation the normalised fields of the FH, and SH, are described by the coupled nonlinear equations. Structures in which both harmonics experience the same sign of group velocity dispersion (GVD) are predicted to support quadratic solitons. Sub-picosecond solitons with peak powers below 100W can be excited in LN nano-waveguides. We analyse different regimes of RR emission due to non-constant GVD in FH and SH, as well as three wave mixing (TWM) radiation driven by soliton interaction with dispersive waves. Our simulations show RR in agreement with our theoretical predictions. These results suggest the possibility of temporal quadratic soliton excitation and novel mechanisms for RR relevant to frequency conversion and supercontinuum generation in LN nano-waveguides.
关键词： dispersive waves,frequency conversion,resonant radiation,nano-waveguides,supercontinuum generation,Lithium Niobate,quadratic solitons
更新于2025-09-16 10:30:52
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[IEEE 2019 21st International Conference on Transparent Optical Networks (ICTON) - Angers, France (2019.7.9-2019.7.13)] 2019 21st International Conference on Transparent Optical Networks (ICTON) - Towards Efficient Nonlinear Plasmonic Metasurfaces
摘要： Nonlinear processes are important in many fields of photonics ranging from biomedical imaging to ultrashort pulse generation. Progress in nanophotonics and metamaterials has created a growing demand for nanoscale nonlinear optical components. However, it is difficult to answer this demand by using traditional materials motivating the search for alternatives approaches. Nonlinear plasmonics has emerged as a viable solution for enabling efficient and nanoscale nonlinear optics. Despite steady progress, so far achieved conversion efficiencies of metamaterials have not yet rivalled conventional nonlinear materials. Here, we discuss our recent progress in development of efficient nonlinear plasmonic metamaterials. Focus is on metasurfaces utilizing collective responses known as surface lattice resonances, which can be used to dramatically boost nonlinear responses of metasurfaces.
关键词： nonlinear metamaterials,surface lattice resonances,metasurfaces,frequency conversion
更新于2025-09-16 10:30:52