Terahertz wave generation is explored on the basis of difference frequency generation in nonlinear optical crystals with a mid-infrared CO_(2) laser.The phase−matching angle and the grating period of periodically inve...Terahertz wave generation is explored on the basis of difference frequency generation in nonlinear optical crystals with a mid-infrared CO_(2) laser.The phase−matching angle and the grating period of periodically inverted GaAs in the 100–1000µm(0.3–3 THz)range are also investigated on the basis of the surface-emitted difference frequency generation.It is found that two schemes of phase-matching-applied collinear phase matching and phase-matching-applied non-collinear phase matching are efficient to obtain THz waves.展开更多
The temperature characteristics of cathode sheath in high-pressure volume discharge are investigated experimentally.The cathode sheath temperatures under various discharge conditions are derived from the speeds of the...The temperature characteristics of cathode sheath in high-pressure volume discharge are investigated experimentally.The cathode sheath temperatures under various discharge conditions are derived from the speeds of the emanating shock waves which are measured by a Mach-Zehnder interferometry.It is found that the cathode sheath temperature and the ratioΔT_(3)/ΔT_(1) of temperature rise between cathode sheath and plasma bulk are determined by the specific energy deposition and the breakdown delay time respectively.These results are helpful for discharge stability improving and shock wave reducing.展开更多
The terahertz(THz)generation based on difference frequency generation in nonlinear optical crystals pumped by mid-infrared C0_(2)laser has been investigated.We present a comprehensive study of the phase-matching condi...The terahertz(THz)generation based on difference frequency generation in nonlinear optical crystals pumped by mid-infrared C0_(2)laser has been investigated.We present a comprehensive study of the phase-matching conditions in the GaSe,ZnGeP_(2)and GaAs crystals.A comparison of the characteristics of these crystals as the THz frequency generator is also presented.The investigation of the conversion efficiency shows that GaSe and GaAs are the most promising nonlinear crystals for the efficient and widely tunable THz generation.展开更多
A simple and convenient terahertz wavemeter based on a Fabry-Perot interferometer (FPI) is presented.The interferometer is composed of two identical Ge etalons,which act as high-reflectance mirrors for terahertz waves...A simple and convenient terahertz wavemeter based on a Fabry-Perot interferometer (FPI) is presented.The interferometer is composed of two identical Ge etalons,which act as high-reflectance mirrors for terahertz waves.The transmission characteristics of the Ge FPI are analyzed using multiple-beam interference theory.The theoretical finesse of the FPI,defined as a ratio of 2π to the phase halfwidth of the transmission fringes,is larger than 12.5.Here,the wavemeter is used to measure the wavelengths of an optically pumped NH3 terahertz laser.The experimental results indicate that the measuring uncertainties are within ±1%.Higher accuracy can be expected if the power or pulse energy of the terahertz source is more stable.展开更多
基金part by the Creative Foundation of Wuhan National Laboratory for Optoelectronics(No Z080007).
文摘Terahertz wave generation is explored on the basis of difference frequency generation in nonlinear optical crystals with a mid-infrared CO_(2) laser.The phase−matching angle and the grating period of periodically inverted GaAs in the 100–1000µm(0.3–3 THz)range are also investigated on the basis of the surface-emitted difference frequency generation.It is found that two schemes of phase-matching-applied collinear phase matching and phase-matching-applied non-collinear phase matching are efficient to obtain THz waves.
文摘The temperature characteristics of cathode sheath in high-pressure volume discharge are investigated experimentally.The cathode sheath temperatures under various discharge conditions are derived from the speeds of the emanating shock waves which are measured by a Mach-Zehnder interferometry.It is found that the cathode sheath temperature and the ratioΔT_(3)/ΔT_(1) of temperature rise between cathode sheath and plasma bulk are determined by the specific energy deposition and the breakdown delay time respectively.These results are helpful for discharge stability improving and shock wave reducing.
基金Supported in part by the Creative Foundation of Wuhan National Laboratory for Optoelectronics(No Z080007).
文摘The terahertz(THz)generation based on difference frequency generation in nonlinear optical crystals pumped by mid-infrared C0_(2)laser has been investigated.We present a comprehensive study of the phase-matching conditions in the GaSe,ZnGeP_(2)and GaAs crystals.A comparison of the characteristics of these crystals as the THz frequency generator is also presented.The investigation of the conversion efficiency shows that GaSe and GaAs are the most promising nonlinear crystals for the efficient and widely tunable THz generation.
基金Supported by Creative Foundation of Wuhan National Laboratory for Optoelectronics(No Z080007).
文摘A simple and convenient terahertz wavemeter based on a Fabry-Perot interferometer (FPI) is presented.The interferometer is composed of two identical Ge etalons,which act as high-reflectance mirrors for terahertz waves.The transmission characteristics of the Ge FPI are analyzed using multiple-beam interference theory.The theoretical finesse of the FPI,defined as a ratio of 2π to the phase halfwidth of the transmission fringes,is larger than 12.5.Here,the wavemeter is used to measure the wavelengths of an optically pumped NH3 terahertz laser.The experimental results indicate that the measuring uncertainties are within ±1%.Higher accuracy can be expected if the power or pulse energy of the terahertz source is more stable.
