For surface hardening of metal,a quasi-Dammann grating (QDG) is proposed and fabricated to generate array spots with proportional-intensity distribution.To get uniformly hardened band distribution and improve the wear...For surface hardening of metal,a quasi-Dammann grating (QDG) is proposed and fabricated to generate array spots with proportional-intensity distribution.To get uniformly hardened band distribution and improve the wear resistance of the sample surface,a three-order QDG is designed to produce array spots with enhanced intensity in the edge.The design and fabrication of the QDG are described in detail.The surface profile of the fabricated grating was measured,which shows that the fabrication error is less than 2%.The laser beam intensity distribution shaped by the QDG was tested by a laser beam analyzer to verify the validity of the QDG.The application of the QDG in the laser surface hardening of metal was experimentally investigated,and the results show that the hardness distribution of the modified layer and the wear resistance of the sample surface are improved significantly by using the QDG.展开更多
Scanning Dammann lithography （SDL） is proposed and implemented, which uses a Danunann grating to generate multiple beams with sharp step boundary for writing large-sized gratings efficiently. One of the most attract...Scanning Dammann lithography （SDL） is proposed and implemented, which uses a Danunann grating to generate multiple beams with sharp step boundary for writing large-sized gratings efficiently. One of the most attractive advantages is that this technique can accelerate tile writing speed, e.g. 1×32 Damnlann grating can be 32 times faster than the single laser scanning system. More importantly, the uniformity of the multi-beams-written lines is much better than the single la.ser beam scanning system in consideration of the environlnental effects such as air turbulence, thermal instability, etc. Using the SDL system, a three-port high-efficiency beam splitter at visible wavelengths is fabricated quickly, and the theoretical and experimental diffraction efficiencies are both higher than 90%. Therefore, SDL should be a useful tool for fabrication of large-sized gratings.展开更多
The excitation of high-order Laguerre–Gaussian（LG） modes in a neodymium-doped yttrium aluminum garnet（Nd:YAG） laser resonator was presented by applying the diffraction of a second-order circular Dammann grating（...The excitation of high-order Laguerre–Gaussian（LG） modes in a neodymium-doped yttrium aluminum garnet（Nd:YAG） laser resonator was presented by applying the diffraction of a second-order circular Dammann grating（CDG） for annular pumping. In the study, the 808 nm pump light was shaped into a double-ring structure by the CDG and matched spatially with that of an ideal LG11 mode. As a result, the laser resonator generated an LG11 vortex mode, and the laser power reached 204 mW with 14.5% slope efficiency. Also, when the cavity mirror was tilted, the laser output could switch to the LG01 vortex mode. The results showed the convenience and versatility of CDG in an annular-pumped vortex laser.展开更多
基金supported by the National Natural Science Foundation of China (Grant No.10832011)the National Science Foundation for Postdoctoral Scientists of China (Grant No.20100470139)
文摘For surface hardening of metal,a quasi-Dammann grating (QDG) is proposed and fabricated to generate array spots with proportional-intensity distribution.To get uniformly hardened band distribution and improve the wear resistance of the sample surface,a three-order QDG is designed to produce array spots with enhanced intensity in the edge.The design and fabrication of the QDG are described in detail.The surface profile of the fabricated grating was measured,which shows that the fabrication error is less than 2%.The laser beam intensity distribution shaped by the QDG was tested by a laser beam analyzer to verify the validity of the QDG.The application of the QDG in the laser surface hardening of metal was experimentally investigated,and the results show that the hardness distribution of the modified layer and the wear resistance of the sample surface are improved significantly by using the QDG.
基金the National Natural Science Foundation of China(Nos.61307064 and 61127013)the Ministry of Science and Technology of the Peo-ple’s Republic of China(No.2012YQ170004).
文摘Scanning Dammann lithography （SDL） is proposed and implemented, which uses a Danunann grating to generate multiple beams with sharp step boundary for writing large-sized gratings efficiently. One of the most attractive advantages is that this technique can accelerate tile writing speed, e.g. 1×32 Damnlann grating can be 32 times faster than the single laser scanning system. More importantly, the uniformity of the multi-beams-written lines is much better than the single la.ser beam scanning system in consideration of the environlnental effects such as air turbulence, thermal instability, etc. Using the SDL system, a three-port high-efficiency beam splitter at visible wavelengths is fabricated quickly, and the theoretical and experimental diffraction efficiencies are both higher than 90%. Therefore, SDL should be a useful tool for fabrication of large-sized gratings.
基金supported by the National Natural Science Foundation of China(No.61475166)
文摘The excitation of high-order Laguerre–Gaussian（LG） modes in a neodymium-doped yttrium aluminum garnet（Nd:YAG） laser resonator was presented by applying the diffraction of a second-order circular Dammann grating（CDG） for annular pumping. In the study, the 808 nm pump light was shaped into a double-ring structure by the CDG and matched spatially with that of an ideal LG11 mode. As a result, the laser resonator generated an LG11 vortex mode, and the laser power reached 204 mW with 14.5% slope efficiency. Also, when the cavity mirror was tilted, the laser output could switch to the LG01 vortex mode. The results showed the convenience and versatility of CDG in an annular-pumped vortex laser.
