Efficient and widely step-tunable terahertz generation with a dual-wavelength CO2 laser

Optical Terahertz Sources Based on Difference Frequency Generation in Nonlinear Crystals

“…Generally, adopting mid-infrared lasers of about 10 µm generated by a bulky and complicated CO 2 laser can achieve a higher output power of terahertz in the DGF process. In 2011, Lu et al reported that the average power of terahertz waves was about 10 µW, and the frequency range was 0.11-4.15 THz pumped with a nanosecond pulse and low-repetition frequency [22]. When a picosecond laser was used as the pump source, the peak power of THz waves could reach 2 MW [23].…”

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] .…”

THz sources based on frequency conversion of multi-line molecular lasers in nonlinear crystals and on optically pumped molecular lasers

“…Therefore, for applications that require high power of terahertz radiation, the use of a CO 2 laser operating at wavelength of 10 µm is more preferable than using solid-state near-IR lasers. At the present time in the scientific literature one can find several papers on the conversion of the frequency of the CO 2 laser radiation in nonlinear crystals to the terahertz range (see, for example, [1][2][3][4][5]). Note that the conversion efficiency of the super high-power CO 2 laser system (UCLA, Neptune Laboratory) under collinear interaction in the GaSe crystal turned out to be lower than for the noncollinear interaction in the GaAs crystal [2], that can be explained by a number of factors: the use of GaSe crystals with low optical quality and realized nonoptimal type of interaction.…”

“…Note that the conversion efficiency of the super high-power CO 2 laser system (UCLA, Neptune Laboratory) under collinear interaction in the GaSe crystal turned out to be lower than for the noncollinear interaction in the GaAs crystal [2], that can be explained by a number of factors: the use of GaSe crystals with low optical quality and realized nonoptimal type of interaction. In practice, CO 2 lasers with much lower energy are usually used, and the use of non-collinear phase matching becomes less effective in this case (see, for example, [3]). In turn, the implementation of collinear phase matching allows one the use of a longer length of nonlinear crystal and an increase conversion efficiency.…”

“…The use of a doped GaSe crystal instead of a pure one, made it possible to increase the conversion efficiency by additional factor of 2 [5]. It should be noted that in papers [1][2][3][4][5] two CO 2 lasers or a two-channel CO 2 laser with independent resonators on the same active medium were used. Usually, the generation of the CO 2 laser radiation occurs only on one spectral line, although a fundamental possibility of generating a CO 2 laser on two or more spectral lines has already been demonstrated (see, for example, the review [6]).…”