A simple terahertz (THz) cavity and a TEA CO 2 laser for the optically pumped THz emission is studied experimentally. To obtain high peak power of pump laser, pressure ratios of gas mixture in the cavity of the TEA CO 2 laser are discussed. When CH 3 OH are pumped by the 9P(16) and 9P(36) CO 2 laser lines, the generation of terahertz radiation with energy as high as 353 µJ and 307 µJ are obtained, respectively. The corresponding photon conversion efficiencies are 0.705% and 0.29%. Meanwhile, higher peak power of pump laser effectively improves the photon conversion efficiency. And the optimum THz laser pressure increases with narrower pulse width of pump laser.
An efficient pulsed CH3OH terahertz (THz) laser pumped by a TEA CO2 laser is investigated experimentally. To improve photon conversion efficiency and THz laser energy, two cavity configurations of the TEA CO2 laser, which is external and semi-external, are evaluated. The pump intensities are about 4.7 MW/cm 2 and 1.2 MW/cm 2 , respectively. Higher pump intensity and more stable single lines are obtained in the external cavity. For the 3.8 J pump energy of the 9P( 16) transition in the external cavity, the maximum terahertz output energy with 570.5 𝜇m wavelength at 160 Pa is 431 𝜇J. With a 6 J energy pulse in terms of a semi-external cavity, a 353 𝜇J terahertz emission (570.5 𝜇m) is produced. The corresponding photon conversion efficiencies are 1.36% and 0.705%, increasing by a factor of about 2.
A high energy pulsed terahertz (THz) laser is studied experimentally. The laser cavity simply consists of a quartz glass waveguide, a coated GaAs input window, and a crystal quartz output window. NH3 is filled in the cavity as gain medium, and pumped by an 8-J line-tunable transversely excited atmospheric (TEA) CO2 laser. When 9R(16) transition acts as the pump line, 55.6-mJ THz radiation (90 µm) is obtained at 730-Pa NH3 pressure. The corresponding conversion efficiency is 13.54%. Energy and optimal pressure of amplified spontaneous emission and laser oscillation are compared.
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