Sponsor(s): Chinese Optical Society；Shanghai Institute of Optics and Fine Mechanics，Chinese Academy of Sciences
12 issues per year
Current Issue: Issue 12, 2019
Chinese Journal of Lasers, regarded as a flag-ship journal in China, reports the most fresh and influential research in the laser field. Founded in 1974, the journal is administrated by Chinese Academy of Sciences (CAS), sponsored by Shanghai Institute of Optics and Fine Mechanics, CAS, and Chinese Optical Society, and published by Chinese Laser Press. The featured columns include laser physics，laser manufacturing，materials and thin films,measurement and metrology ,beam transmission and control, optical communications, biomedical photonics and laser medicine, nonlinear optics, holography and information processing, remote sensing and sensor, spectroscopy, quantum optics, micro and nano optics, terahertz technology, rapid communications, and so on. Chinese Journal of Lasers is indexed in the following databases: EI, Scopus, AJ, CA, INSPEC, CSCD, etc. It has been titled as one of the“100 Chinese Top S&T Journal”,“100 Chinese Outstanding Academic Journal”,“Outstanding S&T Journals of China”,and “The Most International Influencing Academic Journal in China”.
Wang Zhijiang, Xu Zhizhan, Fan Dianyuan, Du Xiangwan
Chen Weibiao, Zhou Shouhuan, Cheng Zhaogu, Liu Zejin, Zhang Xiaoming, Lv Zhiwei, Zhou Jun,
Chinese Journal of Lasers,2019,Vol 46,No. 12
This study experimentally and theoretically examines the response characteristic of twisting the second-azimuthal-order few-mode long-period fiber grating (FM-LPFG). The theoretical analysis shows that the twisting responsivity of the coupled resonant wavelength of the high-order FM-LPFG is closely related to the azimuthal order of the grating, namely the twisting responsivity of the resonant wavelength of the second-azimuthal-order FM-LPFG is almost two times larger than that of the first-azimuthal-order FM-LPFG. The twisting-induced phase mismatching leads to the almost linear decay of the intensity of the resonant peak in the transmission spectrum of the grating with the increase in the grating twisting rate in a relatively small twisting-rate domain. This decay rate is inversely related to the value of the phase mismatch. Further, the experimental results show that the twisting responsivity of the resonant wavelength of the second-azimuthal-order FM-LPFG is approximately 1.5 times larger than that of the first-azimuthal-order FM-LPFG, which reaches 0.72 nm· (rad·m −1) −1 and 0.82 nm· (rad·m −1) −1 in the cases of clockwise and counter-clockwise twisting, respectively. The intensity of the resonant peak varies linearly with the increase in the twisting-rate in the small twisting-rate domain, and the linear sensitivities are 0.81 dB· (rad·m −1) −1 and 0.72 dB· (rad·m −1) −1 in the cases of clockwise and counter-clockwise twisting, respectively. However, the corresponding intensity of the resonant peak has the characteristics of small variation amplitude and fluctuation in the large twisting-rate domain, indicating that experimental results are generally in agreement with the theoretical analysis. These twisting response characteristics of the wavelength and intensity of the resonant peak of the second-azimuthal-order FM-LPFG have potential applications in high-precision sensing of twisting mechanical parameters (such as twisting capacity, twisting speed, and acceleration) and simultaneous measurement of multiple parameters in the same monitoring twisting-rate domain.
Laser-arc hybrid welding process and joint performances of 6106-T6 aluminum alloy profiles for high-speed trains
Chinese Journal of Lasers,2019,Vol 46,No. 12
The hollow extrusion profiles of 6106-T6 aluminum alloy having a lock bottom structure were welded via fiber laser-cold metal transfer (CMT) arc hybrid welding, fiber laser-variable polarity tungsten inert gas (VPTIG) hybrid welding, and fiber laser-melt inert gas (MIG) hybrid welding. Subsequently, a hybrid welding joint with good forming properties and without clear defects was obtained by optimized welding parameters. Furthermore, the joint microstructure, tensile, and fatigue properties were studied, and the fatigue fracture mechanism and fracture morphology were analyzed. The results denote that the sizes of equiaxed grains at the center of the laser-CMT and laser-VPTIG hybrid welding joints gradually decrease from the upper part of the bead to the bottom. However, the sizes of the coarse equiaxed grains in the upper and lower parts do not change considerably, and the sizes of grains at the center of the laser-MIG hybrid welding joint are large. Furthermore, the tensile strength of the laser-CMT, laser-VPTIG, and laser-MIG hybrid welded joints are 213.0 MPa, 198.0 MPa, and 200.0 MPa, respectively. These values denote a certain degree of strength loss when compared with that of the base metal. The fatigue limits of the three hybrid welded joints are 105.00 MPa, 100.83 MPa, and 113.50 MPa, respectively. All the fatigue fracture positions are located in the columnar crystal zone at the fusion line of the welding joints. In addition, the fractures are dimpled, indicating a typical ductile fracture.