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- 摘要
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- 实验方案
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Stark shift in Y <sub/>2</sub> SiO <sub/>5</sub> :Er <sup>3+</sup> by the photon echo beating method
摘要： The coefficient of a linear Stark shift of the 4F9/2–4I15/2 transition of Er3+ ion in Y2SiO5 is measured (14.3 kHz V?1 cm ) by splitting the upper and lower levels of the transition by a pulsed electric field and measuring the splitting frequency from the period of beatings of the temporal form of a photon echo signal (stark photon echo beating method). The linear Stark coefficients of Er3+ transitions in Y2SiO5 have not been measured before, and this is a valuable result for a number of applications such as gradient echo memory, group velocity control via spectral hole burning, etc.
关键词： Er3+,phase control,Stark coefficient,Stark photon echo beating,Y2SiO5,YSO,low electric field pulse
更新于2025-09-23 15:23:52
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Interface Engineering of Au(111) for the Growth of 1T′-MoSe <sub/>2</sub>
摘要： Phase-controlled synthesis of two-dimensional transition metal dichalcogenides (TMDCs) is of great interest due to the distinct properties of the different phases. However, it is challenging to prepare metallic phase of group-VI TMDCs due to their metastability. At the monolayer level, interface engineering can be used to stabilize the metastable phase. Here, we demonstrate the selective growth of either single-layer 1H or 1T’-MoSe2 on Au(111) by molecular beam epitaxy; the two phases can be unambiguously distinguished using scanning tunnelling microscopy and spectroscopy. While the growth of 1H-MoSe2 is favourable on pristine Au(111), the growth of 1T’-MoSe2 is promoted by the pre-deposition of Se on Au(111). The selective growth of 1T’-MoSe2 phase on Se-pretreated Au(111) is attributed to Mo intercalation-induced stabilization of the 1T’ phase, which is supported by density functional theory calculations. In addition, 1T’ twin boundaries and 1H-1T’ heterojunctions were observed and found to exhibit enhanced tunnelling conductivity. The substrate pre-treatment approach for phase-controlled epitaxy should be applicable to other group-VI TMDCs grown on Au (111).
关键词： phase control,heterojunction,scanning tunnelling microscopy/spectroscopy,interface engineering,transition metal dichalcogenides,MoSe2
更新于2025-09-23 15:23:52
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Mixed 2D/3D perovskite with fine phase control modulated by a novel cyclopentanamine hydrobromide for better stability in light-emitting diodes
摘要： The mixed 2D/3D perovskite has been proved to be a promising candidate to increase the exciton binding energy in perovskite light-emitting diodes (PeLEDs). However, the complex phase distribution and impurity (usually referring to ligands) limit the stability of the corresponding PeLEDs. Here, a novel molecule, cyclopentanamine hydrobromide (CyPA·HBr), is adopted to construct a mixed 2D/3D perovskite by partial substitution of FA with CyPA, realizing fine phase control for improved device stability. The adoption of CyPA·HBr helps to tune perovskite grain growth and passivate the defect, resulting in high coverage and smooth thin film with improved photoluminescence property. The PeLEDs with an optimized CyPA·HBr concentration of a molar ratio of 40% exhibit a pure green emission with a full width at half maximum of 22 nm, an external quantum efficiency of 6.55%, and a maximum brightness of 9408 cd m?2 simultaneously. Interestingly, the CyPA·HBr-based device shows a half-lifetime two times longer than the one based on the most commonly used ligand of phenethylammonium bromide (PEA·HBr), assigned to the better phase control ability of CyPA·HBr in 2D/3D perovskite. Those results testify the importance of ligands to modulate perovskite phase along with efficient passivation defects for better stability of PeLEDs.
关键词： Phase control,Stability,Perovskite,Light-emitting diode,Defect passivation
更新于2025-09-23 15:21:01
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Steering second-harmonics
摘要： The phase control and shaping of the second-harmonic radiation generated from an AlGaAs nanodisk antenna has now been accomplished by a team of researchers from Italy, France and Australia. Lavinia Ghirardini and co-workers used electron-beam lithography to fabricate a pair of gratings located either side of a nonlinear nanoantenna. Phase engineering then made it possible to redirect and control the emission angle of second-harmonic light generated from the optically pumped structure. The precise angle of emission can be engineered by employing gratings with different symmetry, or by varying the polarization of the optical pump beam. The control of the emission direction is important because it means that two orders of magnitude more power can be collected out of the antenna plane and arbitrary emission angles could be useful for certain applications. Another key point is that the AlGaAs structures can exhibit lower losses than metallic nanoantennas, which aid efficiency. Such efficient shaping of the nonlinear beams may have applications to, for example, single-photon sources and nonlinear imaging.
关键词： phase control,AlGaAs,nanoantenna,second-harmonics,nonlinear imaging
更新于2025-09-23 15:21:01
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[IEEE 2018 International Conference on Optical MEMS and Nanophotonics (OMN) - Lausanne (2018.7.29-2018.8.2)] 2018 International Conference on Optical MEMS and Nanophotonics (OMN) - Digital Silicon Photonic MEMS Phase-Shifter
摘要： We report on a 4-bit digital silicon photonic MEMS phase-shifter with sub-microsecond switching time and low power consumption (< 10 uW). The device consists of 4 digitally switched phase-shifting units, which in total enable phase shift from (cid:2)(cid:2)(cid:1)/8 to 15pi/8 in increments of (cid:2)(cid:1)/8.
关键词： Silicon Photonic MEMS,Adiabatic Coupler,Phase Control,Photonic Integrated Circuit,Optical Switch
更新于2025-09-23 15:21:01
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[OSA CLEO: Science and Innovations - San Jose, California (2014..-..)] CLEO: 2014 - Arbitrary Carrier-Envelope Phase Control in a 10 kHz, mJ-Class Amplifier
摘要： The carrier-envelope phase of every single shot emitted by a 10 kHz, mJ-class amplifier is measured with a fast spectrometer. A novel high-speed actuator allows arbitrary phase control, with closed-loop integrated phase noise on seed oscillator level (98 mrad, 5.10^5 shots, 50 s).
关键词： Laser amplifiers,Carrier-envelope phase,Ultrafast lasers,Phase control,Amplifier
更新于2025-09-19 17:15:36
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Phase control of quasi-2D perovskites and improved light-emitting performance by excess organic cations and nanoparticle intercalation
摘要： The optoelectronic properties of quasi-two-dimensional organic–inorganic hybrid perovskites can be tuned by controlling the formation of Ruddlesden–Popper type phases, which enables diverse device applications such as photovoltaics and light-emitting diodes (LEDs). Herein, the influence of excess organic cations on the phase formation of (PEA)2MAn?1PbnBr3n+1 is systematically investigated with various mixing ratios to discover the phase distribution beneficial for light-emitting diodes. It is found that PEA cations exceeding Pb ions in molar ratio are required to produce small-n phases in the films with a strong photoluminescence, while excess MA cations enable the formation of more large-n phases. Low electrical conductivity inherent to the properties of quasi-2D perovskites is further lowered by the introduction of excess organic cations. This is overcome by the intercalation of zinc oxide (ZnO) nanoparticles (NPs) into the blocking layers composed of PEA cations. Importantly, these metal oxide NPs also modulate the phase distribution, enabling the realization of bright green quasi-2D perovskites with a better stability and a maximum luminance of nearly 60 000 cd m?2, which is the highest brightness compared to the so far reported quasi-2D perovskite LEDs incorporating organic cations.
关键词： phase control,excess organic cations,nanoparticle intercalation,light-emitting diodes,quasi-2D perovskites
更新于2025-09-19 17:15:36
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[IEEE 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Paris, France (2019.9.1-2019.9.6)] 2019 44th International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - High-resolution frequency and phase control of a terahertz laser
摘要： We report on the high-resolution frequency and phase control of a terahertz (THz) quantum cascade laser (QCL). The 2.0 THz QCL is locked to a stable microwave reference frequency via an all-fibre infrared frequency comb. The frequency of the QCL is controlled by optical injection and the phase is independently controlled by introducing a phase-lock loop that provides electronic feedback to the QCL, forming an optical injection phase locked loop (OIPLL). By implementing this, (1) the instrument limited linewidth of the locked QCL was <1Hz (2) for a fixed frequency, the phase of the THz QCL relative to the microwave reference frequency can be controlled within a range 0.3(cid:2).
关键词： optical injection phase locked loop,phase control,quantum cascade laser,frequency control,terahertz
更新于2025-09-16 10:30:52
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Deep-learning-based phase control method for tiled aperture coherent beam combining systems
摘要： We incorporate deep learning (DL) into tiled aperture coherent beam combining (CBC) systems for the ?rst time, to the best of our knowledge. By using a well-trained convolutional neural network DL model, which has been constructed at a non-focal-plane to avoid the data collision problem, the relative phase of each beamlet could be accurately estimated, and then the phase error in the CBC system could be compensated directly by a servo phase control system. The feasibility and extensibility of the phase control method have been demonstrated by simulating the coherent combining of different hexagonal arrays. This DL-based phase control method offers a new way of eliminating dynamic phase noise in tiled aperture CBC systems, and it could provide a valuable reference on alleviating the long-standing problem that the phase control bandwidth decreases as the number of array elements increases.
关键词： phase control,deep learning,coherent beam combining
更新于2025-09-16 10:30:52
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Spin-decoupled multifunctional metasurface for asymmetric polarization generation
摘要： Integrating multiple functionalities into a single device is a striking field in metasurfaces. One promising aspect is polarization-dependent meta-devices enabled by simultaneous phase control for orthogonally polarized waves. Among these, Pancharatnam-Berry (PB) metasurfaces have drawn enormous interest owing to their natural and robust phase control ability over different circularly polarized waves. However, the phase responses are locked to be opposite with each other, resulting in interrelated functionalities under the circularly-polarized incidence. Here, a generic designing method based on transmission-type dielectric metasurfaces is proposed in the terahertz regime, which breaks this relation by further incorporating dynamic phase with geometric phase, namely, spin-decoupled phase control method. We demonstrate this method by designing and characterizing an efficient multifunctional meta-grating, which splits different circularly polarized waves to asymmetric angles under normal incidences. More importantly, we promote this method by designing several multiplexed meta-gratings for applications of asymmetric polarization generation, which can convert arbitrary linearly polarized wave to two different linearly polarized waves with nearly equal strength and split them to asymmetric angles with a polarization-insensitive efficiency. The designing strategy proposed here shows an impressive robustness and a great flexibility for designing multi-functional metasurface-based devices, and opens new avenues toward modulation of polarization states and the application of metasurfaces in beam steering and polarization multiplexing systems.
关键词： multifunction,dielectric metasurfaces,asymmetric polarization generation,spin-decoupled phase control,terahertz
更新于2025-09-12 10:27:22