- 标题
- 摘要
- 关键词
- 实验方案
- 产品
-
Femtosecond laser-induced non-thermal welding for a single Cu nanowire glucose sensor
摘要： Copper nanowires (CuNWs) are a key building block to facilitate carrier conduction across a broad range of nanodevices. For integration into nanoscale devices, manipulation and welding of these nanowires need to be overcome. Based on high energy density laser processing investigation, we report on innovative welding of single CuNWs to a silver film using a tightly focused laser beam combined with manipulation of CuNWs through the dielectrophoresis (DEP) method. Two types of lasers, femtosecond (FS) and continuous-wave (CW), were employed to analyze, improve, and control Cu-NW melting characteristics under high energy density irradiation. The FS laser welding of CuNWs resulted in a metallic joint with a low contact resistance suitable for functional electronic nanodevices. Computational simulations using the 1-D heat diffusion equation and finite difference method (FDM) were performed to gain an insight into metal–laser interactions for high performance welded contact development. Simulation studies on lasers established contrasting melting behavior of metal under laser irradiation. The device feasibility of CuNW based welded contacts was evaluated in terms of the electrical performance of a glucose sensor. It was possible to sense glucose concentration down to 10?6 M, demonstrating a path towards integration of CuNWs into wearable, flexible nanoelectronic devices.
关键词： glucose sensor,femtosecond laser,Copper nanowires,laser welding,dielectrophoresis,nanoelectronics,continuous-wave laser
更新于2025-09-23 15:19:57
-
Laser-based surface pre-treatment for metal-plastic hybrids using a new process strategy
摘要： In order to join metal-plastic hybrid parts so as to achieve lightweight constructions, innovative joining technologies are essential. For this, thermal joining is a promising approach due to the absence of any joining agent. The joint strength can be increased by surface pre-treatment of the metal with continuous wave laser radiation. Large joining areas, however, are challenging in terms of productivity, efficiency and geometrical flexibility when beam trajectories, which can be easily combined with on-the-fly processing. More precisely, a load direction, and causes lower thermal distortion of the metal sheet than using conventional processing of large areas. In this context, the resulting topography of the metal was analyzed circularly oscillating laser focal spot is geometrically independent of every possible in-plane with respect to the surface roughness and a design criterion was mathematically derived and experimentally validated. Additionally, the joint strength was compared to the strength using conventional beam trajectories. A more promising approach is the use of continuous with a carbon-fiber-reinforced thermoset. The laser-based pre-treatment using the circularly oscillating laser focal spot led to a similar joint strength, while being more productive when resulting from conventional beam trajectories. For verification, steel substrates were joined combined with on-the-fly processing, compared to conventional structuring trajectories.
关键词： surface pre-treatment,continuous wave laser radiation,metal-plastic hybrids,thermal joining
更新于2025-09-23 15:19:57
-
Self-Sufficient and Highly Efficient Gold Sandwich Upconversion Nanocomposite Lasers for Stretchable and Bio-applications
摘要： Multi-functional lanthanides doped upconversion nanoparticles (UCNP) have spread its wings in the fields of flexible optoelectronics and biomedical applications. One of the ongoing challenges lies in achieving UCNP based nanocomposites which enable continuous wave (CW) laser action at ultralow-threshold. Here, gold sandwich UCNP nanocomposites {gold (Au1)-UCNP-gold (Au2)} capable of exhibiting lasing at ultralow-thresholds under CW excitation is demonstrated. The metastable energy-level characteristics of lanthanides is advantageous for creating population inversion. In particular, localised surface plasmon resonance based electromagnetic hotspots in the nanocomposites and the giant enhancement of scattering coefficient for the formation of coherent closed loops due to multiple scattering facilitates the process of stimulated emissions as confirmed by theoretical simulation. The nanocomposites are subjected to stretchable systems for enhancing lasing action (threshold ~0.06 kW/cm2) via light trapping effect. The applications on bioimaging of HeLa cells and antibacterial activity (photothermal therapy) are demonstrated using the newly designed Au1-UCNP-Au2 nanocomposites.
关键词： stretchable lasers,electromagnetic hotspots,random lasing,upconversion laser,solution-processed,continuous-wave laser
更新于2025-09-19 17:13:59
-
Laser polishing of tool steel using a continuous-wave laser assisted by a steady magnetic field
摘要： Continuous-wave (CW) lasers are widely used in laser polishing, but with CW laser polishing, it is difficult to reduce the surface roughness to 0.2 μm from an original value exceeding 1.0 μm. The aim of this study is to develop an innovative method of laser polishing assisted by a steady magnetic field to overcome that bottleneck and produce smoother surfaces. Two experiments confirm the hypothesis that the molten pool overflows during melting peaks to flow into valleys in CW laser polishing, resulting in secondary roughness that causes the aforementioned quality bottleneck. To either reduce or eliminate this secondary roughness, a steady magnetic field is used during CW laser polishing to suppress the overflow of the molten pool. A three-dimensional surface profiler, a scanning electron microscope, and a nanometer indentation tester are used to characterize and analyze the microstructure and properties of the materials. The experimental results show that the Lorentz force due to the steady magnetic field plays an important suppression role in reducing the secondary roughness.
关键词： laser polishing,steady magnetic field,Lorentz force,molten pool overflow,continuous-wave laser,surface roughness
更新于2025-09-19 17:13:59
-
Spectroscopy and diode-pumped continuous-wave laser operation of Tm:Y2O3 transparent ceramic at cryogenic temperatures
摘要： We present the spectroscopic and laser characteristics of a 3 at.% Tm:Y2O3 transparent ceramic at cryogenic temperatures. An absorption cross section of 4.7 × 10?21 cm2 with a bandwidth of 0.7 nm centered at 793.3 nm and an emission cross section of 29.0 × 10?21 cm2 centered at 1930.9 nm were estimated at 80 K. Continuous-wave laser operation was achieved using broadband and VBG stabilized laser diodes emitting around 793 nm as pump sources. With the VBG pump diode, a maximum output power of 6.4 W was achieved at 80 K corresponding to a slope efficiency of 52.0% with respect to absorbed power.
关键词： cryogenic temperatures,diode-pumped,Tm:Y2O3,spectroscopy,continuous-wave laser,transparent ceramic
更新于2025-09-19 17:13:59
-
An ultra-stable 2.9 μm guided-wave chip laser and application to nano-spectroscopy
摘要： We present a configurable guided-wave planar glass-chip laser that produces low-noise and high-quality continuous-wave laser emission tunable from 2.82 to 2.95 μm. The laser has a low threshold and intrinsic power and mode stability attributable to the high overlap of gain volume and pump mode defined by an ultrafast laser inscribed waveguide. The laser emission is single transverse-mode with a Gaussian spatial profile and M2 x,y ～ 1.05, 1.10. The power drift is ～0.08% rms over ～2 h. When configured in a spectrally free-running cavity, the guided-wave laser emits up to 170 mW. The benefit of low-noise and stable wavelength emission of this hydroxide resonant laser is demonstrated by acquiring high signal-to-noise images and spectroscopy of a corroded copper surface film with corrosion products containing water and hydroxide ions with a scattering-scanning near-field optical microscope.
关键词： ultra-stable,continuous-wave laser emission,guided-wave chip laser,nano-spectroscopy,mid-infrared
更新于2025-09-16 10:30:52
-
Nucleate boiling heat transfer performance of different laser processed copper surfaces
摘要： Present study reports the nucleate pool boiling characteristics of micro structured copper surface developed by utilizing two different laser systems, namely, pulsed Nd:YAG laser and continuous wave laser. Tests are conducted at atmospheric pressure and saturation temperature by using water as pool liquid. Enhancement in heat transfer coefficients was observed over all laser processed surfaces. The maximum enhancement in heat transfer coefficient was found to be 136% and 93% for the micro structured surfaces developed by using continuous wave and pulsed laser, respectively, compared to the reference smooth surface. The enhancement in heat transfer performance of micro structured surfaces are due to the presence of surface pores, grooves and micro cavities generated due to laser melting process.
关键词： micro cavities,continuous wave laser,laser ablation,Nd:YAG,nucleate pool boiling,pulsed laser
更新于2025-09-16 10:30:52
-
Performance characterization of continuous-wave laser-induced forward transfer of liquid bioink
摘要： Herein, we propose a continuous-wave laser-induced forward transfer (CW-LIFT) system that possesses high printing quality with a high printing success rate. CW-LIFT can automatically deposit droplets equally and uniformly as a customized pattern. In this study, we selected an 830 nm near-infrared CW laser and applied a 20× microscope objective lens to highly focus the laser beam. In addition, a 16 nm gold thin film was used as the energy-absorbing layer for CW-LIFT. We demonstrated that the CW-LIFT can print liquid bioink and deposit cells in a controlled and precise way.
关键词： bioink,continuous-wave laser-induced forward transfer,laser printing,CW-LIFT,cell deposition
更新于2025-09-11 14:15:04
-
Precision locking CW laser to ultrastable optical frequency comb by feed-forward method
摘要： We locked a 1064 nm continuous wave (CW) laser to a Yb:fiber optical frequency comb stabilized to an ultrastable 972 nm CW laser with the feed-forward method. Consequently, the stability and coherent properties of the ultrastable laser are precisely transferred to the 1064 nm CW laser through the frequency comb’s connection. The relative linewidth of the frequency-stabilized 1064 nm CW laser is narrowed to 1.14 mHz, and the stability reaches 1.5 × 10?17/s at the optical wavelength of 1064 nm. The phase noise characterization in the 1 mHz–10 MHz range is presented to indicate that feed-forward locking a CW laser to an ultrastable comb will offer a potential technique for many important applications, such as optical frequency synthesis and gravitational wave detection.
关键词： feed-forward method,continuous wave laser,phase noise,frequency stability,optical frequency comb
更新于2025-09-11 14:15:04
-
[IEEE 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Honolulu, HI, USA (2018.7.18-2018.7.21)] 2018 40th Annual International Conference of the IEEE Engineering in Medicine and Biology Society (EMBC) - Hybrid multi-wavelength photoacoustic imaging
摘要： Multi-wavelength photoacoustic (PA) imaging has been studied extensively to explore the spectroscopic absorption contrast of biological tissues. To generate strong PA signals, a high-power wavelength-tunable pulsed laser source has to be employed, which is bulky and quite expensive. In this paper, we propose a hybrid multi-wavelength PA imaging (hPAI) method based on combination of single-wavelength pulsed and multi-wavelength continuous-wave (CW) laser sources. By carefully controlling laser illumination sequence (pulse-CW-pulse), and extracting the PA signals’ difference before and after heating of CW lasers, the optical absorption property of multi-wavelength CW lasers could be obtained. Compared with conventional PA imaging, the proposed hPAI shows much lower system cost due to the usage of single-wavelength pulsed laser and cheap CW lasers. Theoretical analysis and analytical model are presented in this paper, followed by proof-of-concept experimental results.
关键词： photoacoustic imaging,continuous-wave laser,multi-wavelength,pulsed laser,hybrid imaging
更新于2025-09-10 09:29:36