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[IEEE 2019 18th International Conference on Optical Communications and Networks (ICOCN) - Huangshan, China (2019.8.5-2019.8.8)] 2019 18th International Conference on Optical Communications and Networks (ICOCN) - A Passively Mode-locked Tm-doped Fiber Laser Based on PbS Nanoparticles as Saturable Absorber
摘要： A passively mode-locked Tm-doped fiber laser was experimentally achieved by using PbS nanoparticles as a saturable absorber (SA), for the first time. The laser delivers stable conventional solitons with pulse duration of 1.24 ps at the repetition rate of 21.93 MHz. The centered wavelength and 3-dB bandwidth are 1957.37 nm and 3.43 nm, respectively. The high signal noise ratio of 61 dB indicates the good stability of the mode-locking. By further increasing pump power, the laser switches into stable second harmonic mode-locked regime. In this state, the average output power of 9.06 mW and repetition rate of 43.86 MHz are obtained. The results reveal that PbS is a type of promising SA for 2 μm ultra-short pulse generation.
关键词： passively mode-locking,PbS nanoparticles,saturable absorber,Tm-doped fiber laser
更新于2025-09-16 10:30:52
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Study of TiO2 nanotubes decorated with PbS nanoparticles elaborated by pulsed laser deposition: microstructural, optoelectronic and photoelectrochemical properties
摘要： Titanium dioxide nanotube arrays (TiO2 NTAs) have been synthesized using the electrochemical anodization procedure. Lead sulfide nanoparticles (PbS NPs) were deposited on TiO2 NTAs (PbS NPs/TiO2 NTAs) using the pulsed laser deposition (PLD) method. The prepared samples (PbS NPs/TiO2 NTAs) were characterized using scanning electron microscopy, transmission electron microscopy (TEM), X-ray diffraction (XRD), UV–Vis spectroscopy and photoluminescence. The size of the PbS NPs was controlled by varying the number of laser pulses (NLP) during the PLD process. TEM observations show that the PbS NPs are in the range of 10–20 nm, consistent with the results obtained from XRD. HRTEM and diffuse reflectivity show that, at NLP ≥ 2500, the growth of the PbS NPs occurs on a previously formed PbS layer. Transmission and absorption spectra show that the PbS-NPs have an indirect optical bandgap which is particle size independent. This optical bandgap corresponds to excitonic transitions, which are greatly affected by oxygen defects, off-stoichiometry and other surface state defects, particularly for smaller NPs (NLP < 2500). The absorption spectra of the TiO2 NTAs show that the PbS NPs extend the absorption range of the TiO2-NTAs from the ultraviolet to the visible region, indicating that the PbS NPs/TiO2 NTAs heterojunction facilitates the separation of the photogenerated charge carriers. Photoelectrochemical analyses show that a maximum photocurrent current density of ~1.05 mA/cm2 and a photoelectrochemical conversion efficiency of 2.5% are reached for NLP = 2500 under an illumination of 100 mW/cm2 in the UV–Vis range.
关键词： TiO2 nanotubes,Photoelectrochemical properties,PbS nanoparticles,PLD
更新于2025-09-16 10:30:52
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Solution-processed P3HT:PbS based NIR Photodetector with FET Configuration
摘要： A near-infrared (NIR) solution-processed photodetector based on a mixture of PbS colloidal quantum dots (CQDs) and Poly(3-hexylthiophene) (P3HT) was presented. In a reverse field-effect transistor (FET) device configuration Au(S,D)/P3HT:PbS/PMMA/Al(G), uniform-sized and well-dispersed PbS CQDs were employed as NIR absorbing materials in the active layer. Meanwhile, the poly(methyl methacrylate) (PMMA) dielectric layer could be seen as an encapsulation to enhance the device stability. Herein, High “on/off” current ratio (Ion/Ioff) of 104 was obtained in dark, and the maximum photosensitivity (P) of 947 was gotten under 200 mW/cm2 980 nm illumination. When the irradiance reduced to 0.1 mW/cm2, the responsivity (R) and detectivity (D?) of the NIR photodetector reached 9.4 mA/W and 2.5×1011 Jones, respectively. Therefore, the P3HT:PbS hybrid FET-based NIR photodetector had shown both relatively high electrical and detecting performance, which provided an experimental foundation and method for the next fabrication of medical infrared detectors and sensors.
关键词： PbS colloidal quantum dots (CQDs),Near-infrared (NIR) photodetector,Poly(3-hexylthiophene) (P3HT),Field-effect transistor (FET)
更新于2025-09-16 10:30:52
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Effect of Cu doping and swift heavy ion irradiation on PbS quantum dots and their applications in solar cells
摘要： Copper ions are incorporated into the PbS quantum dots as dopants via a chemical method and an ion irradiation method. For irradiating the samples, a 100?MeV copper swift heavy ion beam is used with three different doses of 1?×?1011, 3?×?1011, and 1?×?1012?ions/cm2. The doped and irradiated samples are characterised by different techniques and introduced as a sensitising layer in a solar cell. The current density–voltage characteristics of the solar cells are studied under white light illumination conditions and the solar cell parameters such as Jsc, Voc, fill factor, and efficiency are obtained. Efficiency as high as 4.78% is obtained for irradiated quantum dots, which is significantly higher than that of pristine and doped quantum dot solar cells. However, at higher ion dosage, the solar cell efficiency degrades due to unwanted particle agglomeration in quantum dots.
关键词： Cu doping,solar cells,swift heavy ion irradiation,PbS quantum dots
更新于2025-09-16 10:30:52
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Tunable passively Q-switched Dy <sup>3+</sup> -doped fiber laser from 271 to 308??μm using PbS nanoparticles
摘要： We present the first widely tunable passively Q-switched Dy3+-doped ZBLAN fiber laser around 3 μm pumped at 1.1 μm using PbS nanoparticles as the saturable absorber (SA) to our knowledge. At 2.87 μm, the modulation depth and saturation intensity of the SA were measured to be 12.5% and 1.10 MW∕cm2, respectively. Stable Q-switching was achieved over a wavelength range of 2.71–3.08 μm (～370 nm), which is a record tuning range from a pulsed rare-earth-doped fiber laser, to our knowledge. A maximum output power of 252.7 mW was obtained, with a pulse energy of 1.51 μJ, a pulse width of 795 ns, and a repetition rate of 166.8 kHz. This demonstration implies that Dy3+ is a promising gain medium for tunable pulsed sources in the 3 μm band and shows for the first time, to the best of our knowledge, the potential of PbS as a mid-infrared SA.
关键词： Dy3+-doped ZBLAN fiber laser,passively Q-switched,PbS nanoparticles,mid-infrared,tunable
更新于2025-09-16 10:30:52
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Consequence of hot electron of Au and PbS shell thickness on photoa??electrochemical and catalytic activity of ZnO@Au@PbS nanorods for decomposition of toxic organic chemicals and Cr(VI) reduction by UV-to-near-infrared photon harvesting
摘要： In this research work, we have synthesised ZnO@Au@PbS nanorods (NRs) with different shell thickness by a facile chemical method. On introduction of Au nanoparticles (NPs) and PbS shells, the defect emission of ZnO NRs quench and the charge separation process enriches. Under simulated solar light irradiance the photoconductivity and charge transfer efficiency also escalate with Au NPs and PbS shell along with enhancing photocatalytic degradation of organic contaminant. The excitation wavelength dependent catalytic activity confirmed the significant enrichment in photocatalytic activity owing to the synergistic influence of Au NPs and PbS coating on ZnO NRs. The effect of aqueous solution pH and PbS shell thickness on photocatalytic reduction of Cr (VI) has been also explored. The possible charge transfer mechanism during the photocatalytic activity of ZnO@Au@PbS NRs is also proposed and analysed. The catalytic activity, stability and recyclability results revealed that ZnO@Au@PbS NRs are highly favourable and reusable for the environmental remedies.
关键词： UV-to-near-infrared photon harvesting,photocatalytic activity,Cr(VI) reduction,ZnO@Au@PbS nanorods,charge transfer
更新于2025-09-16 10:30:52
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Study of Electrophotophysical Characteristics of IR Photodetectors Based on PbS Colloidal Quantum Dots
摘要： The electrophotophysical characteristics of laboratory samples of IR photodetectors obtained by dip coating of PbS colloidal quantum dots with the subsequent exchange of oleic acid molecules that compose their ligand shell by S2? ions have been studied.
关键词： thin layers,electrophysical characteristics of layers,spectral and luminescent properties,dip-coating method,near infrared region,PbS colloidal quantum dots,ligand exchange,IR photodetectors
更新于2025-09-16 10:30:52
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Chalcogenide || Lead salt photodetectors and their optoelectronic characterization
摘要： Lead salt photoconductors produced by chemical bath deposition are popular IR photodetectors due to their outstanding performance-to-cost ratio, high room temperature performance (D(cid:3) . 1E10) and availability of large area detectors. History of lead salt detectors has been reviewed recognizing some more recent research developments. The chemical bath deposition technique for production of the lead salt detectors has been outlined, followed by a review of the basics for their characterization. Spectral responses of both PbS and PbSe detectors collected in a wide temperature range and properly corrected have been presented.
关键词： PbSe,chemical bath deposition,photoconductors,Lead salt photodetectors,PbS,infrared spectral range
更新于2025-09-16 10:30:52
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Intrinsic exciton photophysics of PbS quantum dots revealed by low-temperature single nanocrystal spectroscopy
摘要： With a tunable size-dependent photoluminescence (PL) over a wide infrared wavelength range, lead chalcogenide quantum dots (QDs) have attracted significant scientific and technological interest. Nevertheless, the investigation of intrinsic exciton photophysics at the single-QD level has remained a challenge. Herein, we present a comprehensive study of PL properties for individual core/shell PbS/CdS QDs emissive near 1.0 eV. In contrast to the sub-meV spectral linewidths observed for II/VI QDs, PbS/CdS QDs are predicted to possess broad homogeneous linewidths. Performing spectroscopy at cryogenic (4 K) temperatures, we provide direct evidence confirming theoretical predictions, showing that intrinsic linewidths for PbS/CdS QDs are in the range of 8-25 meV, with an average of 16.4 meV. In addition, low-temperature, single-QD spectroscopy reveals a broad low-energy side emission attributable to optical as well as localized acoustic phonon-assisted transitions. By tracking single QDs from 4 K to 250 K we were able to probe temperature-dependent evolutions of emission energy, linewidth and line shape. Finally, polarization-resolved PL imaging showed that PbS/CdS QDs are characterized by a 3D emission dipole, in contrast with the 2D dipole observed for CdSe QDs.
关键词： PbS/CdS,bandgap,spectral linewidth,infrared nanocrystals,polarization,single nanocrystal spectroscopy
更新于2025-09-12 10:27:22
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Observation of charge transfer in mixed-dimensional heterostructures formed by transition metal dichalcogenide monolayers and PbS quantum dots
摘要： We report an experimental study on charge transfer properties of mixed-dimensional heterostructures formed by zero-dimensional PbS quantum dots and two-dimensional transition metal dichalcogenides. Monolayers of MoSe2 and MoS2 were fabricated by mechanical exfoliation and chemical vapor deposition techniques, respectively. PbS quantum dots with diameters of 2.3 and 5 nm were synthesized by a hot-injection method and characterized by optical absorption spectroscopy and ultraviolet photoemission spectroscopy. The quantum dots were deposited on the MoS2 and MoSe2 monolayers to form heterostructures. Photoluminescence and transient absorption measurements were performed on the heterostructures as well as individual materials to reveal their photocarrier dynamics. We found that the holes excited in MoSe2 can efficiently transfer to both 2.3- and 5-nm PbS quantum dots, while electrons in these quantum dots cannot transfer to MoSe2. Similar charge transfer properties were observed between MoS2 and the 5-nm PbS quantum dots, while no charge transfer was observed between MoS2 and the 2.3-nm quantum dots. These results provide useful information for understanding the physical mechanism of charge transfer in mixed-dimensional heterostructures and for developing PbS quantum-dot-based mixed-dimensional materials.
关键词： PbS quantum dots,mixed-dimensional heterostructures,transition metal dichalcogenides,photocarrier dynamics,charge transfer
更新于2025-09-12 10:27:22