A theoretical study for femtosecond laser-induced ultrafast electro-absorption of bulk solids is presented.Our numerical results show that,in the case of low intensity of the pump laser where the interaction between t...A theoretical study for femtosecond laser-induced ultrafast electro-absorption of bulk solids is presented.Our numerical results show that,in the case of low intensity of the pump laser where the interaction between the pump laser and solids is in the multi-photon regime,the energy band of solids can be approximately taken as a parabolic band and electro-absorption spectrums from the parabolic band and real band are nearly the same.While,in the case of high intensity where the interaction is in the tunneling regime,spectrums from the parabolic band and real band are quite different.The physical mechanism for the difference in the tunneling regime is found.We find that the non-parabolic parts of the real energy band and Bragger scattering of electrons near the first Brillouin zone boundaries,which are neglected in previous studies,strongly influence the electro-absorption spectrum in the tunneling regime.These two physical processes cause the difference of spectrums.Our theoretical results are in accordance with the experiment result.展开更多
Once the metalenses are fabricated,the functions of most metalenses are invariable.The tunability and reconfigurability are useful and cost-saving for metalenses in realistic applications.We demonstrate this tunabilit...Once the metalenses are fabricated,the functions of most metalenses are invariable.The tunability and reconfigurability are useful and cost-saving for metalenses in realistic applications.We demonstrate this tunability here via a novel hybrid metalens with the strategic placement of an ultra-thin VO;layer.The hybrid metalens is capable of dynamically modulating the focusing intensity of transmitted light at a wavelength of 1550 nm,and demonstrate a 42.28%focusing efficiency of the incident light and 70.01%modulation efficiency.The hybrid metalens’optothermal simulations show an optothermal conversion process of dynamic focusing,and a maximum laser density of 1.76×10^(3)W/cm^(2) can be handled at an ambient temperature lower than 330 K.The hybrid metalens proposed in this work,a light-dose sensitive tunable smart metalens that can protect other instruments/systems or materials from being damaged,has its specific applications such as in anti-satellite blinding,bio-imaging,etc.展开更多
The high repetition rate 10 J/10 ns Yb:YAG laser system and its key techniques are reported.The amplifiers in this system have a multi-pass V-shape structure and the heat in the amplifiers is removed by means of lamin...The high repetition rate 10 J/10 ns Yb:YAG laser system and its key techniques are reported.The amplifiers in this system have a multi-pass V-shape structure and the heat in the amplifiers is removed by means of laminar water flow.In the main amplifier,the laser is four-pass,and an approximately 8.5 J/1 Hz/10 ns output is achieved in the primary test.The far-field of the output beam is approximately 10 times the diffraction limit.Because of the higher levels of amplified spontaneous emission(ASE) in the main amplifier,the output energy is lower than expected.At the end we discuss some measures that can improve the properties of the laser system.展开更多
基金Project supported by the National Natural Science Foundation of China(Grant No.61505023)
文摘A theoretical study for femtosecond laser-induced ultrafast electro-absorption of bulk solids is presented.Our numerical results show that,in the case of low intensity of the pump laser where the interaction between the pump laser and solids is in the multi-photon regime,the energy band of solids can be approximately taken as a parabolic band and electro-absorption spectrums from the parabolic band and real band are nearly the same.While,in the case of high intensity where the interaction is in the tunneling regime,spectrums from the parabolic band and real band are quite different.The physical mechanism for the difference in the tunneling regime is found.We find that the non-parabolic parts of the real energy band and Bragger scattering of electrons near the first Brillouin zone boundaries,which are neglected in previous studies,strongly influence the electro-absorption spectrum in the tunneling regime.These two physical processes cause the difference of spectrums.Our theoretical results are in accordance with the experiment result.
基金Project supported by the National Natural Science Foundation of China(Grant No.61875087)the Innovation and Development Foundation of China Academy of Engineering Physics(Grant No.CX20200020)。
文摘Once the metalenses are fabricated,the functions of most metalenses are invariable.The tunability and reconfigurability are useful and cost-saving for metalenses in realistic applications.We demonstrate this tunability here via a novel hybrid metalens with the strategic placement of an ultra-thin VO;layer.The hybrid metalens is capable of dynamically modulating the focusing intensity of transmitted light at a wavelength of 1550 nm,and demonstrate a 42.28%focusing efficiency of the incident light and 70.01%modulation efficiency.The hybrid metalens’optothermal simulations show an optothermal conversion process of dynamic focusing,and a maximum laser density of 1.76×10^(3)W/cm^(2) can be handled at an ambient temperature lower than 330 K.The hybrid metalens proposed in this work,a light-dose sensitive tunable smart metalens that can protect other instruments/systems or materials from being damaged,has its specific applications such as in anti-satellite blinding,bio-imaging,etc.
文摘The high repetition rate 10 J/10 ns Yb:YAG laser system and its key techniques are reported.The amplifiers in this system have a multi-pass V-shape structure and the heat in the amplifiers is removed by means of laminar water flow.In the main amplifier,the laser is four-pass,and an approximately 8.5 J/1 Hz/10 ns output is achieved in the primary test.The far-field of the output beam is approximately 10 times the diffraction limit.Because of the higher levels of amplified spontaneous emission(ASE) in the main amplifier,the output energy is lower than expected.At the end we discuss some measures that can improve the properties of the laser system.
