The Terahertz （THz） wave is a special electro- magnetic wave with frequency between 0.1 10THz （1 THz=1012 Hz）, which has been widely used in spec- troscopy, imaging and remote sensing. There are several THz wave s...The Terahertz （THz） wave is a special electro- magnetic wave with frequency between 0.1 10THz （1 THz=1012 Hz）, which has been widely used in spec- troscopy, imaging and remote sensing. There are several THz wave sources based on ultrashort laser pulses, including photoconductor antenna, optical Dember effect, air-plasma and optical rectification. For THz generation from optical rectification, phase- matching condition between pump laser pulses and THz pulses has to be fulfilled to obtain a high con- version efficiency.展开更多
When laser intensity varies, the ionization induced by optical field can be described by multiphoton ionization （MPI） in low regime and tunneling ionization （TI） in high regime. An empirical formula was used to fi...When laser intensity varies, the ionization induced by optical field can be described by multiphoton ionization （MPI） in low regime and tunneling ionization （TI） in high regime. An empirical formula was used to fit the ionization happened between these two limitation ionization processes. Based on this, ionization rate and photocurrent induced by two-color femtosecond laser pulses interaction with air-plasma were investigated numerically. It was found that they have different relations with the laser intensity.展开更多
The ionization current generated by two-color laser interaction with different gas atoms can produce strong terahertz （THz） emissions. The ionization potential of atoms determines the ionization rate. Thus, THz emis...The ionization current generated by two-color laser interaction with different gas atoms can produce strong terahertz （THz） emissions. The ionization potential of atoms determines the ionization rate. Thus, THz emission from different atoms varies. Particle-in-cell simulations are conducted to investigate the THz emission from He, Ne, Ar, and N. The THz emissions as a function of the laser field are different because the ionization rate and electron speed depend on the laser field and ionization potential.展开更多
文摘The Terahertz （THz） wave is a special electro- magnetic wave with frequency between 0.1 10THz （1 THz=1012 Hz）, which has been widely used in spec- troscopy, imaging and remote sensing. There are several THz wave sources based on ultrashort laser pulses, including photoconductor antenna, optical Dember effect, air-plasma and optical rectification. For THz generation from optical rectification, phase- matching condition between pump laser pulses and THz pulses has to be fulfilled to obtain a high con- version efficiency.
文摘When laser intensity varies, the ionization induced by optical field can be described by multiphoton ionization （MPI） in low regime and tunneling ionization （TI） in high regime. An empirical formula was used to fit the ionization happened between these two limitation ionization processes. Based on this, ionization rate and photocurrent induced by two-color femtosecond laser pulses interaction with air-plasma were investigated numerically. It was found that they have different relations with the laser intensity.
文摘The ionization current generated by two-color laser interaction with different gas atoms can produce strong terahertz （THz） emissions. The ionization potential of atoms determines the ionization rate. Thus, THz emission from different atoms varies. Particle-in-cell simulations are conducted to investigate the THz emission from He, Ne, Ar, and N. The THz emissions as a function of the laser field are different because the ionization rate and electron speed depend on the laser field and ionization potential.
