- 标题
- 摘要
- 关键词
- 实验方案
- 产品
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Quasi-continuous-wave laser surface melting of aluminium alloy: Precipitate morphology, solute segregation and corrosion resistance
摘要： A quasi-continuous wave laser surface melting is performed on 2219 aluminium alloy to improve the corrosion resistance. The fast cooling rate and the multi-directional solidification behavior of the process transform large and long-chained constituent particles into fine and isolated circular precipitates with alleviated solute segregation. The improved corrosion resistance is due to formation of low-flaw-density passive film, reduction of the driving force for corrosion and improvement of the re-passivation capability of the modified surface. The large and long-chained constituent particles are the preferred sites for corrosion initiation and propagation.
关键词： C: Segregation,B: Polarization,C: Pitting corrosion,A: Aluminium,B: EPMA
更新于2025-11-28 14:24:20
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Polarization-controlled and single-transverse-mode vertical-cavity surface-emitting lasers with eye-shaped oxide aperture
摘要： We presented a single-transverse-mode and single-polarization vertical-cavity surface-emitting laser (VCSEL) with an eye-shaped oxide aperture, obtained by enhanced anisotropic oxidation of oxide layer. For apertures with dimensions of 2 ' 4.6 and 3 ' 6 μm2, the orthogonal polarization suppression ratio (OPSR) of the VCSEL was 22 and 19 dB, respectively. A single-mode suppression ratio (SMSR) of more than 25 dB at an output power of 0.5 mW was also achieved for the VCSEL with aperture dimension of 2 ' 4.6 μm2. We believe that the proposed method to realize the mode and polarization control of VCSELs has great potential in future applications. ? 2018 The Japan Society of Applied Physics
关键词： anisotropic oxidation,single-transverse-mode,VCSEL,single-polarization,eye-shaped oxide aperture
更新于2025-11-28 14:24:03
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Helical Long-Period Gratings Inscribed in Polarization-Maintaining Fibers by CO2-Laser
摘要： We demonstrate fabrication of helical long-period gratings (HLPGs) in a polarization-maintaining fiber using CO2-laser. The maximum polarization dependent loss (PDL) of the grating was measured to be more than 30 dB at the resonance wavelength. The HLPG was found to have a high index sensitivity of -7248.6 nm/RIU when the surrounding refractive index changes in the range of 1.4470-1.4600, temperature sensitivity of 158.8 pm/°C, and strain sensitivity of 3.17 pm/με. The twist sensitivities based on intensity variation were measured to be 5.98 dB/ (rad/m) (co-directional twist) and -5.97 dB/ (rad/m) (contra-directional twist), respectively. The demonstrated grating devices have promising applications as high-sensitivity fiber sensors, PDL compensator etc.
关键词： optical fiber sensors,Fiber gratings,polarization-maintaining fibers,helical long-period gratings
更新于2025-11-28 14:24:03
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High Sensitivity Polarimetric Optical Fiber Pressure Sensor Based on Tapered Polarization-Maintaining and Fiber Bragg Grating
摘要： In this paper, we propose a high sensitivity polarimetric optical fiber pressure sensor (OFPS) using a polarization-diversity loop composed of a polarization beam splitter, polarization controllers, and a sensor head. The sensor head consists of 8-cm-long tapered panda-type polarization-maintaining fiber (PMF) and a fiber Bragg grating (FBG) directly spliced with PMF, and the sensor head is located inside a pressure chamber. A pressure-induced birefringence change due to the photoelastic effect can be greatly enhanced at the tapered section of PMF, thereby increasing the pressure sensitivity of the sensor head. The tapered PMF was fabricated using a fusion splicer, and the tapered length and center waist diameter of the tapered PMF segment were ～350 and ～56.82 μm, respectively. At the polarization-diversity loop, PMF is used as a birefringent element to create an interference spectrum due to polarization interference. A pressure-induced birefringence change of PMF results in a wavelength shift of the interference spectrum. Because the PMF birefringence also has a cross sensitivity to temperature, the FBG is utilized for the compensation of the temperature effect on it. The resonance wavelength of the FBG is sensitive to ambient temperature changes but insensitive to changes in pressure. This spectral response of the FBG can be used to compensate additional ambient temperature changes occurred at the sensor head. The pressure sensitivity of our sensor was measured as approximately ?27.70 nm/MPa, and an adjusted R2 value representing the sensor linearity was measured as ～0.9903 in a measurement range of 0–0.5 MPa. Our fabricated sensor exhibits the highest pressure sensitivity among previously reported polarimetric OFPS.
关键词： Polarization-Maintain Fiber,Optical Fiber Sensor,Sagnac Interferometer,Pressure
更新于2025-11-28 14:24:03
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Multiplexed ultrafast fiber laser emitting multi-state solitons
摘要： Ultrafast fiber lasers have been serving as an ideal playground for spreading the extensive industrial applications and exploring the optics nonlinear dynamics. Here, we report a bidirectional fiber laser scheme for validating the possibility of a multiplexed laser system, which is passively mode-locked by the nonlinear polarization rotation (NPR) technique. In particular, the proposed fiber laser consists of one main cavity and two counter-propagating branches with different dispersion distributions. Thus, different formation mechanisms are introduced into the lasing oscillator. Consequently, stable conventional solitons (CSs) and dissipative solitons (DSs) are respectively formed in the clockwise (CW) and counterclockwise (CCW) directions of the same lasing oscillator. Moreover, attributing to the strong birefringence filtering effect, the wavelength selection mechanism is induced. Through the proper management of intra-cavity birefringence, wideband wavelength tuning and switchable multi-wavelength operations are experimentally observed. The central wavelength of CS can be continuously tuned from 1560 nm to 1602 nm. Additionally, the evolution process of different multi-wavelength operations is also elucidated. Benefiting from this multiplexed laser scheme, bidirectional lasing oscillation, multi-state soliton emission, wavelength tuning and multi-wavelength operations are synchronously realized in a single laser cavity. To the best of our knowledge, it is the first time for such a multiplexed fiber laser has been reported. The results provide information for multifunctional ultrafast fiber laser system, which is potentially set for telecommunications, fiber sensing and optics signal processing, etc.
关键词： multi-wavelength operations,nonlinear polarization rotation,wavelength tuning,Ultrafast fiber lasers,dissipative solitons,conventional solitons
更新于2025-11-28 14:24:03
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All-polarization-maintaining dual-wavelength mode-locked fiber laser based on Sagnac loop filter
摘要： We demonstrate an all polarization-maintaining (PM) fiber based dual-wavelength mode-locked Er-fiber laser. A nonlinear amplifying loop mirror (NALM) with an intracavity nonreciprocal phase shifter is used for self-started mode-locking. A short segment of PM fiber is angle-spliced to the NALM, functioning as a PM Sagnac loop filter, thus enabling dual-wavelength mode-locking. The wavelength separation is solely determined by the angle-spliced PM fiber length. Stable dual-wavelength mode-locking operation is switchable between 1570/1581 nm and 1581/1594 nm. The two-color pulse trains oscillating in the same cavity have an inherent offset repetition rate of ~1 kHz owing to cavity dispersion, allowing future high precision dual-comb applications with a simple and robust configuration.
关键词： polarization-maintaining fiber,dual-comb applications,dual-wavelength mode-locked fiber laser,Sagnac loop filter
更新于2025-11-28 14:24:03
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Nanotube mode-locked, wavelength and pulsewidth tunable thulium fiber laser
摘要： Mode-locked oscillators with highly tunable output characteristics are desirable for a range of applications. Here, with a custom-made tunable filter, we demonstrate a carbon nanotube (CNT) mode-locked thulium fiber laser with widely tunable wavelength, spectral bandwidth, and pulse duration. The demonstrated laser’s wavelength tuning range reached 300 nm (from 1733 nm to 2033 nm), which is the widest-ever that was reported for rare-earth ion doped fiber oscillators in the near-infrared. At each wavelength, the pulse duration can be regulated by changing the filter’s bandwidth. For example, at ~1902 nm, the pulse duration can be adjusted from 0.9 ps to 6.4 ps (the corresponding output spectral bandwidth from 4.3 nm to 0.6 nm). Furthermore, we experimentally and numerically study the spectral evolution of the mode-locked laser in presence of a tunable filter, a topic that has not been thoroughly investigated for thulium-doped fiber lasers. The detailed dynamical change of the mode-locked spectra is presented and we observed gradual suppression of the Kelly sidebands as the filter’s bandwidth is reduced. Further, using the polarization-maintaiing (PM) cavity ensures that the laser is stable and the output laser’s polarization extinction ratio is measured to exceed 20 dB.
关键词： thulium fiber laser,spectral bandwidth,polarization-maintaiing cavity,Kelly sidebands,tunable wavelength,pulse duration,Mode-locked oscillators,carbon nanotube
更新于2025-11-28 14:23:57
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Self-wavelength-sweeping in a bi-directional thulium-doped fiber ring laser
摘要： We report for the first time the self-wavelength-sweeping phenomenon of a bi-directional thulium-doped fiber ring laser. The laser wavelength can spontaneously sweep in both lasing directions at a rate up to 0.2 nm s?1 over 15 nm sweeping range in the 1.95 μm wavelength region. The sweeping rate can be controlled by simply changing the state of polarization of the laser cavity. The laser can be tuned to generate a periodical wavelength-swept output with microsecond pulses in the time domain. The sweep rate can also be tuned to zero to give a static lasing wavelength.
关键词： self-wavelength-sweeping,thulium-doped fiber ring laser,polarization control,bi-directional
更新于2025-11-28 14:23:57
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All-fiber polarization interference filter based uniform multiwavelength erbium-doped fiber laser
摘要： We demonstrate a compact and stable room-temperature multiwavelength erbium doped fiber laser by employing 45° tilted fiber gratings based on an all-fiber polarization interference filter. Benefiting from the filter, the channel number, linewidth, uniformity and stabilization of the multiwavelength laser are greatly improved. The filter also works as a functional polarizing device in a nonlinear polarization rotation, leading to the multiwavelength operation. Instead of a highly nonlinear fiber, the single mode fiber is used to provide enough linearity and to reduce the splice loss. More than 80 wavelengths (within a 3 dB bandwidth), lasing with a linewidth of 0.03 nm and a signal-to-noise ratio of 33 dB, are obtained. The wavelength spacing of 0.164 nm agrees with the channel spacing of the filter, and can be flexibly controlled by adjusting the length of the filter.
关键词： 45° tilted fiber gratings,multiwavelength fiber laser,all-fiber polarization interference filter (AFPIF)
更新于2025-11-28 14:23:57
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Multi-wavelength oscillating and transverse mode switching in an all few-mode fiber laser based on polarization manipulation
摘要： We have proved the polarization dependence of the fiber Bragg grating (FBG), and demonstrated an all few-mode fiber laser that can realize multi-wavelength oscillation and switchable transverse modes simultaneously based on the polarization dependence of FBG. In this fiber laser, single-, dual- and triple-wavelength oscillation can be realized by merely adjusting the polarization controller inside the cavity. Three output transverse modes including fundamental mode, second-order mode, and hybrid modes can be switched as the laser operates at three different single-wavelengths correspondingly. In addition, azimuthally and radially polarized beams can be easily generated. This all few-mode fiber laser scheme may play a more significant role in wavelength division multiplexed (WDM) systems, mode division multiplexed (MDM) systems, sensing, and so on.
关键词： Polarization dependence,Multi-wavelength,Transverse mode,Fiber laser
更新于2025-11-28 14:23:57