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Analysis of optical injection on red and blue laser diodes for high bit-rate visible light communication
摘要： In this work, self-injection and external-injection in ～450 nm InGaN/GaN blue and ～650 nm InGaP/AlGaInP red diode lasers are investigated. A distinct locking characteristic is observed in the self-injection case with small 19 cm cavity length, demonstrating enhanced ～2.34 and ～2.07 GHz 3-dB bandwidths, corresponding to a factor of ～1.4 and ～1.1 improvement, and reduced ～60 and ～80 pm spectral linewidths, for the blue and the red lasers, respectively. Moreover, this short external cavity self-injection locked system exhibited superior performance by a factor of 1.1–1.3 compared to the long cavity (26 cm) configuration. Conversely, the external optical injection exhibited weak locking signature with improved linewidths by a factor of ～1.6–2.8 and reaching as small as ～70 and ～87 pm for the blue laser, respectively, while almost doubling in the peak powers. Later, on–off keying modulation technique based data transmission rates of up to 3.5 and 4.5 Gb/s are demonstrated on free-running blue and red laser diodes, respectively, employing an in-house laser diode mount based system. Moreover, owing to the bandwidth limitation of the optically injected systems, successful transmission of up to 2 Gb/s is demonstrated with better performance compared to the respective free-running cases, in particular, the external-optically injected system demonstrated more than double improvement in the bit-error-rate.
关键词： Visible light communication,Semiconductor laser diodes,External optical injection,Self-injection locking
更新于2025-11-28 14:23:57
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High Power Laser‐Driven Ce <sup>3+</sup> ‐Doped Yttrium Aluminum Garnet Phosphor Incorporated Sapphire Disc for Outstanding White Light Conversion Efficiency
摘要： A facile synthesis method for the development of Y3 (cid:2) xAl5O12:xCe3t (0.03–0.24) yellow phosphor via an auto-combustion method and fabrication of phosphor-incorporated sapphire disc (PISD) of various dimensions is reported. The photoluminescence (PL) intensity for the optimized concentration of Ce3t-doped yttrium aluminum garnet (YAG) phosphor is recorded at 550 nm wavelength under the excitation wavelength of 445 nm from a high power blue laser diode. The developed PISD exhibits high stability and luminescence. The blue laser diode is a promising candidate to revolutionize the luminous intensity of the white light by several orders of magnitude as compared with the existing blue light-emitting diodes. This emerging technology has an extremely bright future with endless uses of tunable power of the laser that controls the intensity of the emitted white light. Hence, this new approach provides a paradigm shift to produce highly ef?cient white light based on PISD integrated with blue laser diode as compared with the conventional technology. Moreover, such con?gurations allow more styling and packaging ?exibility that reduces the overall size of the fabricated unit and makes it favorable for various lighting applications.
关键词： blue laser diodes,photoluminescence,optical geometry,white light conversion,yellow phosphor
更新于2025-11-21 11:18:25
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Low Power Consumption Red Light-Emitting Diodes Based on Inorganic Perovskite Quantum Dots under an Alternating Current Driving Mode
摘要： Inorganic perovskites have emerged as a promising candidate for light-emitting devices due to their high stability and tunable band gap. However, the power consumption and brightness have always been an issue for perovskite light-emitting diodes (PeLEDs). Here, we improved the luminescence intensity and decreased the current density of the PeLEDs based on CsPbI3 quantum dots (QDs) and p-type Si substrate through an alternating current (AC) driving mode. For the different driving voltage modes (under a sine pulsed bias or square pulsed bias), a frequency-dependent electroluminescent (EL) behavior was observed. The devices under a square pulsed bias present a stronger EL intensity under the same voltage due to less thermal degradation at the interface. The red PeLEDs under a square pulsed bias driving demonstrate that the EL intensity drop-off phenomenon was further improved, and the integrated EL intensity shows the almost linear increase with the increasing driving voltage above 8.5 V. Additionally, compared to the direct current (DC) driving mode, the red PeLEDs under the AC condition exhibit higher operating stability, which is mainly due to the reducing accumulated charges in the devices. Our work provides an effective approach for obtaining strong brightness, low power consumption, and high stability light-emitting devices, which will exert a profound in?uence on coupling LEDs with household power supplies directly.
关键词： low power consumption,perovskite quantum dots,silicon,light emitting diodes,alternating current driving
更新于2025-11-21 11:01:37
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P‐type Sb‐doped Cu <sub/>2</sub> O Hole Injection Layer Integrated on Transparent ITO Electrode for Acidic PEDOT:PSS‐Free Quantum Dot Light Emitting Diodes
摘要： It is developed that transparent p-type Sb-doped cuprous oxide (ACO) integrated Sn-doped In2O3 (ITO) film as hole injection layer (HIL) and anode combined electrodes for quantum dot light emitting diodes (QD-LEDs) to substitute acidic PEDOT:PSS HIL based electrode. By graded co-sputtering of ACO and ITO targets, the graded p-type ACO buffer layer can be integrated on the surface region of the ITO electrodes. P-type conductivity of the ACO film for acting as effective HIL in QD-LEDs is confirmed by a positive Hall coefficient (1.74 (cid:1) 10 (cid:3)1). Due to the well-matched work function of p-type ACO on the ITO electrodes, the acidic PEDOT:PSS-free QD-LEDs exhibited typical current-voltage-luminescence of QD-LEDs. The successful operation of PEDOT:PSS-free QD-LED with p-type ACO integrated ITO electrode indicates that ACO and ITO anode graded sputtering is simpler fabrication steps for cost-effective QD-LEDs and elimination of interfacial reactions caused by the acidic PEDOT:PSS layer for reliable QD-LEDs.
关键词： Sn-doped In2O3,acidic PEDOT:PSS,hole injection layer,p-type conductivity,Sb-doped Cu2O,quantum dots light emitting diodes
更新于2025-11-21 10:59:37
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Robust CsPbX <sub/>3</sub> (X = Cl, Br, and I) perovskite quantum dot embedded glasses: nanocrystallization, improved stability and visible full-spectral tunable emissions
摘要： Currently, all inorganic perovskite quantum dots (QDs) of cesium lead halides (CsPbX3, X = Cl, Br, and I) have been mainly fabricated using wet chemical methods. Unfortunately, applications of perovskite QDs have been limited due to their poor stability. In the present work, the in situ growth of whole-family CsPbX3 (X = Cl, Br, and I) perovskite QDs in Zn–P–B–Sb based oxide glass via a glass crystallization strategy is reported. The as-prepared CsPbX3 QDs@glass nanocomposites exhibit typical excitonic recombination emissions and superior chemical stability benefited from the protection of the robust inorganic glass matrix. Through modifying the molar ratio of halide sources in glass, multi-color tunable emissions in the entire visible spectral range of 400–750 nm are achieved. As a result, light-emitting diode devices can be constructed by coupling blue-emissive CsPbBrCl2, green-emissive CsPbBr3 and red-emissive CsPbBr0.5I2.5 QDs@glass powders with a commercial ultraviolet chip, yielding bright white light luminescence with excellent optoelectronic performance.
关键词： stability,light-emitting diodes,tunable emissions,glass crystallization,perovskite quantum dots
更新于2025-11-20 15:33:11
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Efficient White LEDs Using Liquid-state Magic-sized CdSe Quantum Dots
摘要： Magic clusters have attracted significant interest to explore the dynamics of quantum dot (QD) nucleation and growth. At the same time, CdSe magic-sized QDs reveal broadband emission in the visible wavelength region, which advantageously offer simple integration of a single-type of nanomaterial and high color rendering ability for white light-emitting diodes (LEDs). Here, we optimized the quantum yield of magic-sized CdSe QDs up to 22% via controlling the synthesis parameters without any shelling or post-treatment process and integrated them in liquid-state on blue LED to prevent the efficiency drop due to host-material effect. The fabricated white LEDs showed color-rendering index and luminous efficiency up to 89 and 11.7 lm/W, respectively.
关键词： Magic clusters,Quantum dots,Luminous efficiency,CdSe,White light-emitting diodes
更新于2025-11-20 15:33:11
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Thermal Stability of LED Molecules Triphenylamine-Based Aromatic Polyamides: Spectral and Electrochemistry Applications
摘要： By using the aromatic nucleophilic displacement reaction of 4-fluorobenzonitrile with three aniline-derivatives using sodium hydride as the base synthesized new dinitriles intermediates (A-CN), (B-CN) and (C-CN). After alkaline hydrolysis of these resultants three di acid monomers e.g., 4,4'-dicarboxy-4''-ethylenetriphenylamine (A-OH), 4,4'-dicarboxy-4''-isopentyl-triphenylamine (B-OH), 4'-dicarboxy-4''-phenoxy-triphenylamine (C-OH) were obtained. A series of poly(amine-amide)s were prepared by the phosphorylation poly-condensation reaction with different aromatic diamines. The chemical structures of all the resultant compounds and poly(amine-amide)s were identified by FTIR, 1H and 13C NMR techniques. These aromatic poly(amine-amide)s exhibited excellent thermal stability with high glass transition temperatures (Tg). Solutions diluted in N-methyl pyrrolidone of these polyamides appeared a strong UV-visible absorption in the blue region. These polymers exhibited cyclic voltammetry of the resulting polyamides films cast onto an ITO-coated glass substrate in dry acetonitrile containing 0.1 M of tetrabutylammonium perchlorate as an electrolyte exhibited one oxidation redox couples.
关键词： LED-molecules,Emitting diodes,Thin layer
更新于2025-11-19 16:56:42
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Synthesis, Photophysical and Electroluminescent Properties of Iridium(III) Complexes with 2-Aryl-thiazole and Oxadiazol-substituted Amide Derivative Ligands
摘要： By using aryl-thiazole as cyclometalated ligand and oxadiazol-substituted amide as ancillary ligand, three novel iridium(III) complexes have been synthesized and characterized, and the photophysical and electrochemical properties have been investigated. Complexes 1–3 exhibit efficient phosphorescence emissions at 542, 555 and 585 nm with photoluminescence quantum yields (PLQYs) of 0.04, 0.03 and 0.02 in CH3CN solutions, respectively. In the 10 wt% doped 2,4-diphenyl-6-bis(12-phenylindolo)[2,3-a]carbazole-11-yl)-1,3,5-triazine (Dictrz) film, the PLQYs (0.88 for complex 1, 0.47 for complex 2 and 0.37 for complex 3) increase significantly owing to the great restriction of rotations and vibrations in rigid host. The organic light-emitting diodes based on these complexes show good performance with the maximum current efficiencies of 20.06, 22.20 and 13.45 cd A-1 and maximum power efficiencies of 13.54, 17.31 and 9.48 lm W?1 with the CIE coordinates of (0.46, 0.53), (0.49, 0.50) and (0.59, 0.40) for complexes 1?3, respectively.
关键词： Iridium complex,Aryl-thiazole,Organic light-emitting diodes,Oxadiazol-substituted amide
更新于2025-11-19 16:56:35
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[IEEE 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - Shanghai (2018.8.8-2018.8.11)] 2018 19th International Conference on Electronic Packaging Technology (ICEPT) - A Synthetic Method for Extremely Stable Thin Film of CsPbBr<inf>3</inf> QDs and its Application on Light-emitting Diodes
摘要： The ability to be mixed with the polymers is very important for applications of perovskite quantum dots (QDs), such as in display, lighting and so on. Here, a method for fabricating a thin film composed of CsPbBr3 QDs and polydimethylsiloxane (PDMS) was reported. By using the ethyl acetate, a large number of ligands on the surface were removed and the combination with polymers can realize. Based on the thin film, an LED device was assembled and its luminous flux, luminous efficiency, color temperature and CIE color coordinates were measured. What’s more, the thin film revealed a splendid stability after being stored for 42 days without any protection, which show the broad prospects of it.
关键词： Inorganic perovskite quantum dots,Stability,Light-emitting diodes
更新于2025-11-19 16:46:39
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Electrochemical capacitance-voltage profiling of nonuniformly doped GaAs heterostructures with SQWs and MQWs for LED applications
摘要： Light-emitting heterostructures with single and multiple GaAs/InGaAs quantum wells have been investigated by means of electrochemical capacitance-voltage (ECV) profiling. Capacitance-voltage characteristics were measured; concentration profiles of free charge carriers over the heterostructure depth as well as the intensity of quantum well filling by charge carriers were obtained. In heterostructures with a single quantum well (QW) we considered limitations of capacitance techniques for undoped QW profiling, which is situated near the metallurgic border of the p–n –junction. We made a detailed consideration of phenomena related to Debye smearing and we developed and analyzed the dependence of the space charge region width on the doping. Special attention was paid to investigation of the “blind” area. This was inspired by the practical problem from capacitance spectroscopy of semiconductors, when the researcher poses the task of obtaining a free charge carrier depth distribution profile as deep as possible in the space charge region, i.e. where the intensity of the electric field is maximum. Generally, the active QW of a LED heterostructure is placed deep in the space charge region, so reaching these regions is extremely important for practical problems. We present an evolution of capacitance-voltage characteristics during ECV profiling of nonuniformly doped p – n– heterostructures. For a heterostructure with multiple quantum wells we registered a response from 6 QWs.
关键词： capacitance-voltage profiling,heterostructure,quantum well,nonuniform doping,Electrochemical capacitance-voltage profiling,quantum dot,light-emitting diodes
更新于2025-11-14 17:28:48