The wavelength-tunable and switchable narrow bandwidth mode-locking operation is demonstrated in an all fiber laser based on semiconductor-saturable absorber mirror （SESAM）. Two narrow-band fiber Bragg gratings cent...The wavelength-tunable and switchable narrow bandwidth mode-locking operation is demonstrated in an all fiber laser based on semiconductor-saturable absorber mirror （SESAM）. Two narrow-band fiber Bragg gratings centered at 1029.9nm and 1032nm respectively with a polarization controller inserted between them are used to realize the wavelength switchable between 1029.9nm and 1032nm. The laser delivers different pulse widths of 7.5ps for 1030nm and 20ps for 1032nm. The maximum output power for both could reach -6.5mW at single pulse operation. The output wavelength couM be tuned to about 0.gnm intervals ranging from 1030.2nm to 1031.1 nm and from 1032.15nm to 1033.7nm with the temperature change of the fiber Bragg grating, respectively.展开更多
The effect of pulse width on near-infrared supercontinuum generation in nonlinear fiber amplifier is investigated theoretically and experimentally. The complex Ginzburg–Landau equation and adaptive split-step Fourier...The effect of pulse width on near-infrared supercontinuum generation in nonlinear fiber amplifier is investigated theoretically and experimentally. The complex Ginzburg–Landau equation and adaptive split-step Fourier method are used to simulate the propagation of pulses with different pulse widths in the fiber amplifier, and the results show that a longer pulse is more profitable in near-infrared supercontinuum generation if the central wavelength of the input laser lies in the normal dispersion region of the gain fiber. A four-stage master oscillator power amplifier configuration is adopted and the output spectra under picosecond and nanosecond input pulses are compared with each other. The experimental results are in good accordance with the simulations which can provide some guidance for further optimization of the system.展开更多
烟丝的宽度是衡量卷烟质量的重要指标,为了能够实时把控烟丝质量,该文设计一种烟丝宽度实时在线检测方法。该文将YOLOv4中的SPP和PANet结构进行融合,并将输出三种输出尺度改为一种输出尺度,使改进后的YOLOv4算法结构更加简单,在性能几...烟丝的宽度是衡量卷烟质量的重要指标,为了能够实时把控烟丝质量,该文设计一种烟丝宽度实时在线检测方法。该文将YOLOv4中的SPP和PANet结构进行融合,并将输出三种输出尺度改为一种输出尺度,使改进后的YOLOv4算法结构更加简单,在性能几乎不下降的情况下,运算速度提升近35%;烟丝宽度计算方法是该文设计的MCS(Moving Center Search)中心移动搜索法。该方法能够自动搜索出烟丝的两个侧边,并较为精确地计算出烟丝宽度,计算精度可达0.2毫米。将MCS烟丝宽度计算方法与该文改进后的YOLOv4模型相结合,能够进行实时在线的烟丝宽度检测,实时把控烟丝生产质量,提升生产效率。展开更多
We demonstrate a flexible erbium-doped pulsed fiber laser which achieves the wavelength and pulse width tuning by adjusting an intracavity filter. The intracavity filter is flexible to achieve any of the different wav...We demonstrate a flexible erbium-doped pulsed fiber laser which achieves the wavelength and pulse width tuning by adjusting an intracavity filter. The intracavity filter is flexible to achieve any of the different wavelengths and bandwidths in the tuning range. The wavelength and width of pulse can be tuned in a range of - 20 nm and from - 0.8 ps to 87 ps, respectively. The flexible pulsed fiber laser can be accurately controlled, which is insensitive to environmental disturbance.展开更多
基金Supported by the National High Technology Research and Development Program of China under Grant No 2014AA041901NSAF Foundation of the National Natural Science Foundation of China under Grant No U1330134+1 种基金the Opening Project of Shanghai Key Laboratory of All Solid-State Laser and Applied Techniques under Grant No 2012ADL02the National Natural Science Foundation of China under Grant Nos 61308024 and 11174305
文摘The wavelength-tunable and switchable narrow bandwidth mode-locking operation is demonstrated in an all fiber laser based on semiconductor-saturable absorber mirror （SESAM）. Two narrow-band fiber Bragg gratings centered at 1029.9nm and 1032nm respectively with a polarization controller inserted between them are used to realize the wavelength switchable between 1029.9nm and 1032nm. The laser delivers different pulse widths of 7.5ps for 1030nm and 20ps for 1032nm. The maximum output power for both could reach -6.5mW at single pulse operation. The output wavelength couM be tuned to about 0.gnm intervals ranging from 1030.2nm to 1031.1 nm and from 1032.15nm to 1033.7nm with the temperature change of the fiber Bragg grating, respectively.
基金supported by the National Natural Science Foundation of China(Grant Nos.11404404 and 11274385)the Outstanding Youth Fund Project of Hunan Provincethe Fund of Innovation of National University of Defense Technology,China(Grant No.B120701)
文摘The effect of pulse width on near-infrared supercontinuum generation in nonlinear fiber amplifier is investigated theoretically and experimentally. The complex Ginzburg–Landau equation and adaptive split-step Fourier method are used to simulate the propagation of pulses with different pulse widths in the fiber amplifier, and the results show that a longer pulse is more profitable in near-infrared supercontinuum generation if the central wavelength of the input laser lies in the normal dispersion region of the gain fiber. A four-stage master oscillator power amplifier configuration is adopted and the output spectra under picosecond and nanosecond input pulses are compared with each other. The experimental results are in good accordance with the simulations which can provide some guidance for further optimization of the system.
文摘烟丝的宽度是衡量卷烟质量的重要指标,为了能够实时把控烟丝质量,该文设计一种烟丝宽度实时在线检测方法。该文将YOLOv4中的SPP和PANet结构进行融合,并将输出三种输出尺度改为一种输出尺度,使改进后的YOLOv4算法结构更加简单,在性能几乎不下降的情况下,运算速度提升近35%;烟丝宽度计算方法是该文设计的MCS(Moving Center Search)中心移动搜索法。该方法能够自动搜索出烟丝的两个侧边,并较为精确地计算出烟丝宽度,计算精度可达0.2毫米。将MCS烟丝宽度计算方法与该文改进后的YOLOv4模型相结合,能够进行实时在线的烟丝宽度检测,实时把控烟丝生产质量,提升生产效率。
基金Project supported by the National Natural Science Foundation of China(Grant No.61575137)the Program on Social Development by Department of Science and Technology of Shanxi Province,China(Grant No.20140313023-3)
文摘We demonstrate a flexible erbium-doped pulsed fiber laser which achieves the wavelength and pulse width tuning by adjusting an intracavity filter. The intracavity filter is flexible to achieve any of the different wavelengths and bandwidths in the tuning range. The wavelength and width of pulse can be tuned in a range of - 20 nm and from - 0.8 ps to 87 ps, respectively. The flexible pulsed fiber laser can be accurately controlled, which is insensitive to environmental disturbance.
