A 1.35 mJ ammonia Fabry–Perot cavity terahertz pulsed laser with metallic capacitive-mesh input and output couplers

An efficient ammonia Fabry–Perot (F–P) cavity terahertz (THz) laser has been studied experimentally in this article. The input and output couplers also served as sealed windows fabricated by depositing nickel capacitive metallic meshes on ZnSe and high-resistivity silicon substrates have been constructed as a F–P oscillator. Using the THz laser, the properties related to THz pulsed laser such as beam profile, delay, the minimum pump intensity, THz lasing threshold and THz atmospheric transmission have been investigated. Further, the factors such as pump intensity and gas pressure influencing the efficiency of THz laser have also been discussed. Finally, the highest output pulse energies of 1.35 mJ at 90μm operating at 1.09 kPa ammonia pressure pumped by a 402 mJ TEA CO2 laser with 9R (16) line have been generated, and photon conversion efficiencies of 6.5% have been achieved.