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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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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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Pulsed-laser-deposited lead sulfide nanoparticles based decoration of porous silicon layer as an effective passivation treatment for multicrystalline silicon
摘要： We report on the use of pulsed laser deposition (PLD) of PbS nanoparticles (PbS-NPs) on porous silicon layers in order to passivate multicrystalline silicon (mc-Si) substrates intended for solar cells applications. The porous silicon (PS) layer was first obtained through the electrochemical anodization of the mc-Si substrate, and then the PLD technique was used to decorate the PS layer by PbS-NPs at room temperature. By varying the number of laser ablation pulses (NLP) from 50 to 1200, the average size of the PbS-NPs was varied from ~2 nm to ~10 nm. The X-ray diffraction analysis has confirmed the crystalline quality of the PbS-NPs, whereas the transmission electron microscopy observations showed the uniform decoration of the PS by the PbS-NPs. By combining different characterization techniques, we were able to identify NLP = 200 as the optimal decoration condition that leads to the best passivation, in terms of the lowest surface reflectivity (of 15% at 500 nm wavelength), the highest PL intensity of the PS layer (centered around 633 nm) and the longest minority carrier lifetime (as long as ~430 μs versus 40 μs for the bare treated PS layer and 2.2 μs for the untreated bare mc-Si).
关键词： Pulsed laser deposition,Porous silicon,Solar cells,PbS nanoparticles,Surface passivation
更新于2025-09-12 10:27:22