Difference-frequency generation of intense femtosecond pulses in the mid-IR using HgGa/sub 2/S/sub 4/ and AgGaS/sub 2/

Na2Hg3M2S8 (M = Si, Ge, and Sn): New Infrared Nonlinear Optical Materials with Strong Second Harmonic Generation Effects and High Laser-Damage Thresholds

“…For instance, HgGa 2 S 4 crystallizes in tetragonal I4̅ space group with a "defect" chalcopyrite structure and has shown good application in high-power ultrafast laser system with large NLO coefficient (d 36 = 34 pm/V) and high damage resistance. 46,47 BaHgS 2 belongs to NCS space group (Pmc2 1 ) with two different types of Hg atoms (HgS 4 tetrahedron and linear-like HgS 2 unit) in its structure and appears large SHG response (d 33 = −59.7 pm/V) about fivetimes that of benchmark AgGaS 2 . 48 αand β-K 2 Hg 3 M 2 S 8 (M = Ge, Sn) crystallize in different space groups (α, Aba2; β, C2), and β-phase exhibits good NLO coefficient (d eff = 20 pm/V) and large laser-damage threshold (LDT).…”

Parametric generation and characterization of femtosecond mid-infrared pulses in ZnGeP_2

“…In ZGP pumped at 2 µm by the idler beam of a 800-nm pumped OPA, tuning from 2.5 to 10 µm was demonstrated [17]. Maximum energies of 9 µJ near 4 µm and >1 µJ in the entire tuning range up to 12 µm were reported [18], where HgGa 2 S 4 (HGS) was used as a nonlinear crystal. Tunable mid-IR pulse generation through difference-frequency generation (DFG) between the signal and the idler pulses of a 800-nm pumped OPA is commonly achieved with AGS, which allows continuous tuning from 2.4 µm to wavelengths longer than 12 µm [19].…”

Parametric cascade downconverter for intense ultrafast mid-infrared generation beyond the Manley-Rowe limit

“…Recent results that produce intense pulses at kilohertz repetition rates have demonstrated wavelength tuning up to 20 m, pulse durations around 100 fs, and pulse energies of more than 2 Ja t1 0m. [3][4][5][6][7] Improving DFM MIR power conversion efficiency is constrained by the basic limitation quantified by the Manley-Rowe relations, 8 which show that the number of photons output at MIR wavelengths cannot exceed the number of pump photons input; the uppermost quantum efficiency (QE) of the DFM process is 100%. 9 The beams involved in DFM are classified pump, signal, and MIR in order of increasing wavelength.…”

“…For example, Rotermund and co-workers reported internal quantum efficiencies from 30% to 80% over the MIR wavelength range of 4 -12 m through DFM in AgGaS 2 and HgGa 2 S 4 . 3 The MIR generation is accompanied by large signal power amplification that is often not documented. Figure 1, recorded using the source described previously, 6 provides a typical result for the nonlinear crystal GaSe.…”