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Beta-lead oxide quantum dot (β-PbO QD)/polystyrene (PS) composite films and their applications in ultrafast photonics
摘要： Polymer composite films, particularly those based on polymers and layered nanomaterials, are attractive materials for exploiting the properties of multiple materials for applications in electronics and photonics. In this work, a beta-lead oxide quantum dot (β-PbO QD)/polystyrene (PS) composite film is successfully fabricated by a solution blending method. The β-PbO QDs are well-distributed within a β-PbO QD/PS composite film and the composite film is transparent and flexible. Owing to the almost complete insolubility of both β-PbO QDs and PS, the as-fabricated β-PbO QD/PS composite film holds the nonlinear photonic response from 540 nm to 1060 nm under complete water immersion, confirming its excellent stability to high humidity. Additionally, the β-PbO QD/PS composite film exhibits a considerable capacity for optical modulation owing to a strong nonlinear absorption coefficient compared with those of other two-dimensional (2D) materials. On the basis of a home-made β-PbO QD/PS composite film saturable absorber, stable mode-locked pulses at 1060 nm are generated under humid conditions. It is anticipated that the β-PbO QD/PS composite films enable the exploitation of new waterproof, flexible photonic devices based on functional 2D materials and polymers.
关键词： composite films,mode-locked pulses,ultrafast photonics,polystyrene,nonlinear absorption,beta-lead oxide quantum dot
更新于2025-11-19 16:56:42
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Broadly Tunable Plasmons in Doped Oxide Nanoparticles for Ultrafast and Broadband Mid-Infrared All-Optical Switching
摘要： Plasmons in conducting nanostructures offer the means to efficiently manipulate light at the nanoscale with subpicosecond speed in an all-optical operation fashion, thus allowing for constructing high performance all-optical signal-processing devices. Here, by exploiting the ultrafast nonlinear optical properties of broadly tunable mid-infrared (MIR) plasmons in solution-processed, degenerately doped oxide nanoparticles, we demonstrate ultrafast all-optical switching in the MIR region, which features with subpicosecond response speed (with recovery time constant of ?400 fs) as well as ultrabroadband response spectral range (covering 3.0-5.0 μm). Furthermore, with the degenerately doped nanoparticles as Q-switch, pulsed fiber lasers covering 2.0-3.5 μm were constructed, of which a watt-level fiber laser at 3.0 μm band show superior overall performance among ever-reported passively Q-switched fiber lasers at the same band. Notably, the degenerately doped nanoparticles show great potential to work in the spectral range over 3.0 μm that is beyond the accessibility of commercially available but expensive semiconducting saturable absorber mirror (SESAM). Our work demonstrates a versatile while cost-effective material solution to ultrafast photonics in the technologically important MIR region.
关键词： tunable plasmons,ultrafast photonics,all-optical switching,doped oxide nanoparticles,mid-infrared
更新于2025-09-23 15:21:21
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Cuprous Sulfide for Different Laser Pulse Generation: Q-Switching and Mode-Locking
摘要： As a new type of copper-based chalcogenide two-dimensional nanomaterial, cuprous sulfide (Cu2S) has attracted much attention due to its unique band structure and optical properties. In this paper, all-fiber ring laser at the 1.53 μm regime with two kinds of Cu2S saturable absorber devices is demonstrated. The self-started Q-switched pulse with a central wavelength of 1530 nm was obtained for the first time by using Cu2S deposited on the fiber jumper as SA. When the tapered fibers deposited with Cu2S are used to replace the jumpers in the cavity, it can be found that the loss is significantly reduced and a mode-locked pulse with a pulse width of 896 fs has been achieved via evanescent field interaction. This experiment further enriches the application of Cu2S nanosheets in pulsed lasers and promotes the development and application of metal sulfides in nonlinear optics and ultrafast photonics.
关键词： saturable absorber,cuprous sulfide,mode-locking,Q-switching,ultrafast photonics,Cu2S,nonlinear optics
更新于2025-09-23 15:19:57
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Photo-chemically derived Plasmonic Semiconductor Nanocrystals as Optical Switch for Ultrafast Photonics
摘要： Establishing new photonic material with large optical nonlinearity in the near-infrared regime is significant for ultrafast optical science and devices. In this paper, we developed a facile photochemical approach to fabricate covellite CuS plasmonic nanocrystals (NCs) with high chemical stability and strong oxidation resistance under ambient conditions. The photo-chemically derived CuS NCs possess strong absorption in the visible-to-near-infrared optical range caused by the localized surface plasmon resonance effect (LSPR). We further demonstrate superior saturable absorption behavior of CuS NCs with large modulation depth and high damage threshold. By using CuS as an optical switch, a highly-stable mode-locked pulsed laser operating in the telecommunication band with signal-to-noise ratio over 70 dB and pulse duration of 1.57 ps has been achieved. Our results suggest that the photochemical method is an effective technique to fabricate plasmonic NCs, which can be developed as an excellent candidate for ultrafast photonic devices in the visible-to-near-infrared region.
关键词： Optical switch,CuS nanocrystals,Photochemical synthesis,Ultrafast photonics,Plasmonic semiconductor nanocrystals
更新于2025-09-23 15:19:57
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Wideband saturable absorption in Metal-organic frameworks (MOFs) for mode-locking Er- and Tm-doped fiber laser
摘要： We fabricate a Metal-organic frameworks (MOFs) Saturable absorber (SA) based on a microfiber. Nonlinear optical absorption of the MOF SA is characterized systmatically. The modulation depth is measured to be 6.57 % and 14.25 % at 1.5 and 2 μm spectral ranges, respectively. We report ultrashort pulse generation in both Er- and Tm-doped fiber lasers by using a same microfiber-based MOF SA, operating 384 fs and 1.3 ps pulse duration at 1563 nm and 1882 nm, respectively. To the best of our knowledge, this is the first report on a MOF based fiber laser at near infrared spectral ranges. Our findings validate the applicability of MOF as a broadband SA for ultrafast photonic applications.
关键词： Ultrafast photonics,Saturable absorber,Metal-organic frameworks,Fiber laser,Nonlinear optical absorption
更新于2025-09-16 10:30:52
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Heavily doped Semiconductor Colloidal Nanocrystals as Ultra-Broadband Switches for Near Infrared and Mid-Infrared Pulse Lasers
摘要： Heavily self-doped semiconductors can be designed to use for advanced photonics due to both fabrication and functional advantages. Ultrafast response, strong optical nonlinearity, broadband wavelength range and accessibility of integration are major challenges for ultrafast all-optical photonics operating in infrared wavelength range. Here, solution-processed Cu1.8Se semiconductor nanocrystals (NCs) demonstrate ultrafast response (about 360~520 fs), strong optical nonlinearity (as large as -1.4×103 cm GW-1) and broadband (from 800 to 3000 nm) nonlinear optical absorption in the near-infrared and mid-infrared wavelength range. The ultrafast response and larger optical nonlinearity may be triggered by the plasma ground-state bleaching in the strong surface electromagnetic filed. Stable Q-switched lasers in Er-doped fiber laser, Tm-doped fiber laser and Ho/Pr co-doped ZBLAN fiber laser are operated, respectively. These findings indicate that Cu1.8Se NCs are prospective nonlinear materials for ultrafast response and broadband pulse laser.
关键词： semiconductor nanocrystals,ultrafast photonics,optical modulation,superbroadband,nonlinear optical
更新于2025-09-16 10:30:52
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Harmonic Mode-Locking in Bidirectional Domain-Wall Soliton Fiber Lasers
摘要： We report on the first experimental observation of passively harmonic mode-locking (HML) in a bidirectional domain-wall dark-soliton fiber laser. The domain-wall solitons (DWSs) are characterized, in which, the strong coupling between the two directions takes great responsibility for the generation. By appropriately altering the polarization state in the cavity, the stable fundamental domain-wall solitons and HML states could be obtained and switched with increasing the pump power. In our experiment, the repetition rate can be tunable from the fundamental mode locking of 2.96 MHz up to eighth-order HML of 23.68 MHz when the pump power is increased from 120 to 542.5 mW. Importantly, this HML operation of dark-pulse DWSs confirms that the DWSs are the intrinsic feature of the mode-locked lasers, as well as the conventional bright solitons. This work could provide a new perspective to the understanding of the formation and transformation of dark solitons, which may also find great potential applications in fiber sensing and future optical communication systems.
关键词： lasers and laser optics,mode-locked lasers,ultrafast photonics,pulse propagation and temporal solitons
更新于2025-09-12 10:27:22
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Graphdiyne for Ultrashort Pulse Generation in an Erbium-Doped Hybrid Mode-Locked Fiber Laser
摘要： An erbium-doped hybrid passively mode-locked ?ber laser based on few-layer graphdiyne (GDY) saturable absorber (SA) has been investigated for the ?rst time. Hybrid mode-locked ?ber laser is composed of non-linear polarization rotation (NPR) technology and GDY-SA. The central wavelength, pulse width and repetition rate of the output pulse are 1530.7 nm, 690.2 fs and 14.7 MHz, respectively. Compared with the passively mode-locked pulse laser with GDY-SA or NPR technology alone, the output pulse width of hybrid passively mode-locked ?ber laser is reduced more than 50 fs. It is demonstrated that the performance of GDY can be potentially applied in ultrafast laser.
关键词： saturable absorber,?ber laser,ultrafast photonics,mode-locked,graphdiyne
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) - Airy Plasmon Pulses Investigated by Multiphoton Photoemission Electron Microscopy (PEEM)
摘要： Airy wave packets are a special class of non-diffractive solutions to the wave equation which accelerate along a bend trajectory. Their self-healing property makes them particularly interesting for integrated nanophotonic applications. Surface plasmon polaritons (SPPs), in contrast, have the beneficial property to be bound to the two-dimensional surface of a noble metal and enable sub-wavelength confinement. In two dimensions, Airy wave packets are the only non-diffracting solution of the wave equation. The high intrinsic bandwidth of a plasmonic excitation makes it ideal for ultrafast photonics. Photoemission Electron Microscopy (PEEM) represents an ideal tool to deliver images of these processes. The method has been successfully applied by us in the past to investigate the transient behavior of an optical nanoantenna emitting Hankel plasmon pulses. We have used PEEM in combination with a variable wavelength excitation from an optical parametric chirped pulse amplifier system (OPCPA) to experimentally investigate Airy plasmon pulses emitted by an excitation grating. The OPCPA system allows us to experimentally investigate the performance of the excitation in the wavelength range between 670 and 840 nm, where a 3-photon-process is necessary to emit an electron. In this way, we can sample the spectral response which is necessary to determine the ultrafast characteristics of the Airy plasmon pulse. We find that the excitation of stationary Airy plasmons is possible over a large bandwidth. However, the creation of an ultrafast hotspot requires also a matching of the spectral phase which is hard to fulfill in strong dispersing systems. We therefore accompany our measurements with rigorous finite-difference time domain simulations, a suitable nonlinear electron yield model, and analytic calculations to determine the modal purity of the Airy plasmon excitation based on reciprocity. Results support our experimental data and suggest that further improvements of the excitation scheme are necessary to obtain spatio-temporal hotspots.
关键词： PEEM,Surface plasmon polaritons,SPPs,ultrafast photonics,Multiphoton Photoemission Electron Microscopy,Airy plasmon pulses
更新于2025-09-11 14:15:04
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Hafnium Sulfide Nanosheets for Ultrafast Photonic Device
摘要： Group IVB transition metal dichalcogenides (TMDs) have attracted significant interests in photoelectronics due to their predictable superior physical properties compared to group VIB (Mo and W) TMDs. However, the nonlinear optical properties and ultrafast photonic devices based on group IVB TMDs remained unexplored so far. Herein, the nonlinear optical absorption of HfS2 nanosheets (NSs) prepared by liquid exfoliation is demonstrated. The usage of HfS2 as a new ultrafast photonic device for high-energy and ultrashort pulse generation in a fiber laser is reported for the first time. A photonic crystal fiber (PCF) assisted deposition method is presented for the fabrication of an HfS2-microfiber integrated saturable absorber (SA) device with precisely controllable light–matter interaction, which can benefit the output of the device. The HfS2-microfiber SA device shows modulation depth of 15.7% and exhibits outstanding ultrashort pulse generation performance with pulse duration of 221.7 fs in the communication band. The experimental results suggest that HfS2 presents highly nonlinear optical absorption and can be developed into an excellent candidate of SA devices for the development of HfS2-based ultrafast photonics.
关键词： nonlinear optics,hafnium sulfide,ultrafast photonics
更新于2025-09-04 15:30:14