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Bandgap trimming and optical properties of Si <sub/>3</sub> N <sub/>4</sub> :Al microbelt phosphors for warm white light-emitting diodes
摘要： Si3N4:Al microbelts with tunable bandgap energy and resultant yellow-orange phosphors are prepared through a facile direct nitridation method. The bandgap energy of Si3N4:Al microbelts has been gradually trimmed from 2.58 eV to 2.67, 2.74 and 2.85 eV by regulating the Si/Al molar ratio from 1000 : 1 to 50 : 1. Si3N4:Al:Eu phosphors display a wide emission ranging from 500 to 800 nm when excited by a 450 nm blue LED light source. The crystal structure of Si3N4:Al microbelts is of the α-Si3N4 phase as characterized by X-ray diffraction, high-resolution TEM and crystal models. Si3N4:Al microbelts grow along the (012) stacking direction in a low doping concentration case and grow along the (011) stacking direction in a high doping concentration case. Theoretical calculation results show that Al prefers to occupy the low energy interstitial sites in the (012) plane. There are more substitutional sites in the (011) plane occupied by Al in the high doping concentration case with increasing the bandgap energy of Si3N4:Al. Warm white light emission has been achieved by precoating Si3N4:Al:Eu phosphors onto a blue LED chip, whose correlated color temperature (CCT) can be tailored from 3000 K to 6500 K by altering the phosphor amount, indicating a promising potential application of Si3N4:Al:Eu phosphors in warm white LEDs.
关键词： direct nitridation method,Si3N4:Al microbelts,tunable bandgap energy,yellow-orange phosphors,warm white LEDs
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) - 8×8 Programmable Si <sub/>3</sub> N <sub/>4</sub> Photonic Processor for Linear Quantum Processing
摘要： Universal linear optical networks made of on-chip tunable beam splitters and phase shifters form a very promising platform for quantum information processing (QIP). Thanks to their phase stability and reconfigurability, they are robust and enable a variety of quantum information and communication protocols such as quantum teleportation, quantum key distribution, photonic qubit gate protocols and boson sampling. We introduce an 8×8 mode Blass matrix as universal transformation circuit for linear-optical quantum information processing implemented on stoichiometric Si3N4 waveguides. The Si3N4 platform offers the unique combination of high index contrast, ultralow straight-propagation loss and a spectrally wide transparency range. In order to demonstrate that the photonic chip works as a linear-optical processor suited for general-purpose quantum information processing, we program on-chip quantum interference on several beam splitters within the Blass matrix and demonstrate a high visibility interference, obtaining an average fidelity of ~95%. To further demonstrate the flexibility and configurability of our processor we realized an 8-dimensional unitary transformation with single photons in an 8 dimensional rail encoding. Our findings demonstrate the suitability and reliability of a low-loss, integrated linear optical photonic processor based on Si3N4 waveguides. These results show the high potential of Si3N4 for the development of large universal linear optical quantum circuits, which is essential for the progress of quantum information processing.
关键词： Si3N4 waveguides,Blass matrix,linear optical networks,quantum information processing,quantum interference
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) - Photonic Chip-Based Soliton Microcomb Driven by a Compact Ultra-Low-Noise Laser
摘要： Photonics chip-based soliton microcombs have been used in many applications including LIDAR, spectroscopy, coherent communication and astronomical spectrometer calibration [1]. Current-initiated soliton microcombs have been demonstrated [2, 3] recently, signifying improvements in the fabrication of high-Q Si3N4 microresonators. However, both approaches suffer from limited input laser power, thus only demonstrated single-soliton at repetition rates above 149 GHz, which are challenging to detect with commercially available photodetectors. Here we demonstrate a single-soliton generation in 100-GHz-FSR Si3N4 microresonators fabricated using the photonic Damascene reflow process [4], yielding the intrinsic Q-factor exceeding 15 million [5]. Using a compact hybrid laser with narrow linewidth, low relative intensity noise (–160 dBc/Hz at foffset=100 kHz) and high output power up to 100 mW [6], different comb states are observed by simply changing the current of the laser diode, without the need of complex tuning mechanism such as a single sideband modulator [7]. As the laser noise is directly transferred to the soliton comb line, this low-noise laser can be utilized in applications where the phase noise is a critical parameter, e.g. low-noise microwave generation or coherent communication. The experimental setup shown in Fig. 1 (a) consists of an ULN laser operated by a current source and temperature controllers to tune its frequency and power. After the light is coupled into the Si3N4 photonic chip via double inverse nano tapers [8], the temperature of FBG/GC is changed to align the laser wavelength to the resonance of the microresonator. The laser diode current is increased (≈ 330 mA) until soliton existence range is sufficiently long. This is indicated by transmission signal directly observed after the chip on the photodetector (Fig. 1 c). Due to high-Q factor of the Si3N4, the soliton state can be accessed via simply frequency forward tuning [9], without the need of any complex soliton tuning mechanism. Further, different comb states are observed, i.e. modulation instability, multi-soliton state and single-soliton state, via laser diode current tuning. The coherence properties of the soliton-comb teeth is asserted by performing a heterodyne beatnote measurement using a reference laser with a short-time linewidth of 10 kHz (Fig. 1b). The soliton spectrum is fitted with a sech2 function corresponding to a 3 dB bandwidth of ≈19.3 nm and a ≈131.5 fs pulse.
关键词： astronomical spectrometer calibration,Photonics chip-based soliton microcombs,photonic Damascene reflow process,low-noise microwave generation,Si3N4 microresonators,LIDAR,compact hybrid laser,coherent communication,single-soliton generation,spectroscopy
更新于2025-09-11 14:15:04
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[Laser Institute of America ICALEO? 2016: 35th International Congress on Applications of Lasers & Electro-Optics - San Diego, California, USA (October 16–20, 2016)] International Congress on Applications of Lasers & Electro-Optics - Alteration of fracture toughness (KIC) following laser shock peening of silicon nitride ceramics
摘要： This work focuses on the development in laser shock peening (LSP) Si3N4 ceramics with a view to first observe the general effects namely; the topography, hardness, flaw size, plane strain fracture toughness (KIc). Firstly, an LSP surface treatment was conducted to establish a crack-free surface treatment. This also established a parametric window and elucidated the feasibility of treating a brittle material such as Si3N4 with a high intensity/pressure surface treatment such as LSP. Upon comparing the as-received surface with the LSPned surface elucidated a natural increase in surface roughness from an average of 1.73μm to 4.79μm. This indicated some level of material removal. In addition, a decrease in hardness was found by 4.5% and an increase in the KIc by over 21.5% through a possible induction of plasticity within the Si3N4. The microstructure of the Si3N4 also showed considerable changes after LSP surface treatment and a possible α-beta transformation were introduced which indicated surface strengthening. The work undertaken herein have shown that with further refinement of the LSP parameters, this type of laser treatment could be beneficial for strengthening advanced ceramics, particularly, as the process offers a mechanism for enhancement in fracture toughness. An alteration of such an important property of a Si3N4 would open new avenues for its applications particularly where metals and alloys fail.
关键词： hardness,surface treatment,Laser shock peening,Si3N4 ceramics,fracture toughness
更新于2025-09-11 14:15:04
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[IEEE 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz2018) - Nagoya, Japan (2018.9.9-2018.9.14)] 2018 43rd International Conference on Infrared, Millimeter, and Terahertz Waves (IRMMW-THz) - Characteristics of VOx Microbolometer on Si<inf>3</inf>N4/SiO<inf>2</inf> Membrane Fabricated by Deep-RIE and XeF2 Vapor Etching for THz-detectors
摘要： VOx thin films were fabricated on Si3N4/SiO2/Si substrates by metal-organic decomposition (MOD). Then, a VOx microbolometer was fabricated on a Si3N4/SiO2 membrane. A membrane was realized by dry etching of the backside of the Si substrate using a Deep-RIE and XeF2 vapor etching with a good reproducibility. The DC sensitivity of the bolometer on membrane was 2310 W-1. This value was about 15 times higher than that of the VOx microbolometer on the Si3N4/SiO2/Si substrate and about two orders of magnitude higher than that of the Bi microbolometer on a dielectric substrate.
关键词： Si3N4/SiO2 membrane,THz-detectors,VOx microbolometer,Deep-RIE,XeF2 vapor etching
更新于2025-09-09 09:28:46
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[IEEE 2017 IEEE 12th Nanotechnology Materials and Devices Conference (NMDC) - Singapore (2017.10.2-2017.10.4)] 2017 IEEE 12th Nanotechnology Materials and Devices Conference (NMDC) - Measurements of Polyimide/Silicon Nitride nanocomposite interphase
摘要： According to recent studies on electrical insulation systems, the nanocomposite organic/inorganic hybrid materials (NC) assure a distinct improvement of their high-temperature functioning and allow strengthening the dielectric properties of these systems. Recently it was shown that some modifications of the electrical properties such as the permittivity, dielectric breakdown and materials lifetime, were often awarded to the properties of what it is called the interphase. This interphase represents the interaction zone between the nanoparticles and the matrix and plays very often a leading part in the definition of the macroscopic properties. In this paper, Atomic Force Microscopy (AFM) is used to make, at the same time, qualitative and quantitative measurements of these interaction zones. For example, Peak Force Quantitative Nano Mechanical (PF QNM) mode, would allow to highlight the presence of the interphase by measuring mechanical properties (Young’s modulus, deformation and adhesion). As a result, this new and original study on Polyimide/Silicon Nitride (PI/Si3N4) nanocomposite confront experimental results with theoretical models.
关键词： Polyimide,PF-QNM,AFM,Nanocomposite,Si3N4 nanofillers,Interphase,Nanodielectrics
更新于2025-09-09 09:28:46