Tunable terahertz generation from one CO2 laser in a GaSe crystal

Study on the generation of Efficient Terahertz from cavity phase matching optical parametric oscillator with a GaAs Crystal sheet by CO2 laser

“…The relation of the optimized cavity length in a GaAs crystal sheet Λ at room temperature and the THz wavelength are shown in Fig.1 from Eqs. (3) and (4). It can be seen that Λ is increased from 0.16 to 1.96 mm when THz wavelength is increased from 100 to 1000µm in the CPM scheme.…”

“…Among the variety of nonlinear crystals, GaAs meet the requirements for high transparency in both 10 µm band and relatively high transparency in the THz region. A lot of work has been carried out enhancing THz power [ [4][5][6][7]. We demonstrate a tunable THz source based on the collinear DFG in GaSe crystal with a dual-wavelength CO 2 laser [7].…”

“…A peak power of 182 mW was detected, which peak power corresponds to be external power conversion efficiency only about 1×10 -5 %. Optical parametric oscillation(OPO) is one of the effective ways to produce high-power, narrow-band coherent THz sources in nonlinear crystals [4]. Optical parametric oscillation(OPO) was designed to satisfy the wave vector phase matching condition in nonlinear crystal.…”

First-principles calculation of the structural, electronic, elastic, and optical properties of sulfur-doping ε -GaSe crystal

“…The strong covalent bonding within the multi-layer and weak van der Waals bonding between the multi-layers make ε-GaSe a quasi-two-dimensional, highly anisotropic material with a birefringence of about 0.35 in the infrared range. [1] Combining its other excellent performances, such as large nonlinear coefficient (54 pm/V at 10.6 µm), wide transparency range (0.62 µm-18 µm) and high damage threshold, ε-GaSe have been successfully used to generate coherent laser radiation in an extremely wide spectral range from mid-to far-infrared [2][3][4][5] and further to terahertz regions [6][7][8] by nonlinear frequency conversion. On the other hand, the layer structure of ε-GaSe results in its pronounced cleavability and almost zero hardness; its bad mechanical properties lead to uncontrolled layer stacking defects (an admixture of γ, δ or β polytypes) in the growth process and hamper the cutting and polishing along arbitrary directions, which holds back its outof-lab applications in nonlinear optics.…”

Terahertz generation in quasi-phase-matched GaAs wafers by pulse CO2laser

“…However, all of the reported DFG terahertz sources pumped by CO 2 lasers were established with two lasers [4,10], made the system huge and complex. Previously we have reported an tunable THZ sources based on DFG in GaAs wih one CO2 laser, the THz pulse of a peak power 35 W was obtained using non-collinear phase matching in a 20mm length GaAs crystal, and acquired the THz pulse of a peak power 182 mW using collinear phase matching in a 8mm length GaSe crystal [8][9] .…”