title: Terahertz parametric generation and amplification from potassium titanyl phosphate in comparison with lithium niobate and lithium tantalate.
abstract: We report superior terahertz parametric generation from potassium titanyl phosphate (KTP) over congruent-grown lithium niobate (CLN) and lithium tantalate (CLT) in terms of parametric gain and laser damage resistance. Under the same pump and crystal configurations, the signal emerged first from KTP, 5% Mg-doped CLN, CLN, and then finally from CLT. The signal growth rate in KTP was comparable to that in 5%-Mg-doped CLN, but the signal power from KTP reached a much higher value after all the other crystals were damaged by the pump laser. We further demonstrate seeded terahertz parametric amplification in an edge-cut KTP at 5.74 THz. The THz parametric amplifier (TPA) employs a 17-mm long KTP gain crystal, pumped by a passively Q-switched pump laser at 1064 nm and seeded by a continuous-wave diode laser tuned to the signal wavelength at 1086.2 nm. With 5.8-mJ energy in a 520-ps pump pulse and 100-mW seed signal power, we measured 5-W peak-power THz output from the KTP TPA with 22% pump depletion. In comparison, we measured no detectable THz output power from a similar edge-cut CLN TPA under the same pump power, detection scheme, and crystal configuration, when tuning the seed laser wavelength to 1072.2 nm and attempting to generate a radiation at 2.1 THz.
authors.forename: Ming-Hsiung
authors.initials: MH
authors.lastname: Wu
authors.forename: Yu-Chung
authors.initials: YC
authors.lastname: Chiu
authors.forename: Tsong-Dong
authors.initials: TD
authors.lastname: Wang
authors.forename: Gang
authors.initials: G
authors.lastname: Zhao
authors.forename: Andrius
authors.initials: A
authors.lastname: Zukauskas
authors.forename: Fredrik
authors.initials: F
authors.lastname: Laurell
authors.forename: Yen-Chieh
authors.initials: YC
authors.lastname: Huang