Generation of continuously tunable, 5–12 µm radiation by difference frequency mixing of output waves of a KTP optical parametric oscillator in a ZnGeP₂ crystal

Abstract

Signal and idlers waves obtained from a Nd : YAG laser pumped KTP optical parametric oscillator (OPO) are difference frequency mixed in a ZnGeP2 (ZGP) crystal to generate radiation in the mid-infrared. The KTP OPO is operated in the type-II phase matching mode, and the extraordinary and ordinary waves are tunable from 1.76 µm to 2.36 µm and from 2.61 µm to 1.90 µm, respectively. The orthogonally polarized waves are difference frequency mixed in a ZGP crystal to generate mid-IR radiation tunable from 5 to 12 µm.

Development of a mid-infrared tunable optical parametric oscillator pumped by a Q-switched Tm,Ho:YAG laser

“…However, the application fields of the MIR tunable lasers have been restricted by their large size and high cost equipments. Although the OPO is more suitable for the miniaturization of the MIR tunable lasers, most MIR-OPOs have been pumped at the wavelength of 2-3 µm generated with another OPO pumped by a Nd:YAG laser at the wavelength of 1.064 µm [12][13][14][15][16] . Since such tandem OPO configurations complicate equipments and their overall efficiencies are low, MIR-OPOs directly pumped by a laser with a wavelength of 2-3 µm generated by lamp-pumped Ho:YLF, Er,Cr,Tm:YSGG, and Cr,Tm,Ho:YAG lasers have been reported [17][18][19][20] .…”

Adhesive-free bond quasi-noncritical phase-matched and quasi-phase-matched optical parametric oscillations

“…They are also important pump sources for midinfrared and terahertz (THz) radiations [3][4][5][6][7]. However, the spatial walk-off in critical phase-matched (CPM) OPO's can present a severe problem resulting in high threshold and distorted beam quality.…”

“…For example, the walk-off angle of the extraordinary beam in a 1.064-μm pumped 2-μm KTP OPO can be as high as 2.68°. As a result, large-scale pump lasers with pulse energy at least above several millijoules are usually required [3,4]. In order to reduce the OPO threshold and increase its efficiency, a common method is using a walk-off compensated (WOC) KTP pair to replace the single KTP crystal, in which oppositely oriented KTP crystals can be arranged separately [5] or bonded together [6,8,9].…”

Mid-infrared tunable optical parametric oscillator pumped by a Q -switched Tm,Ho:YAG ceramic laser

“…However, the applicable fields of the MIR tunable lasers have been restricted by their large size and high cost equipments. Although the OPO is most suitable for the miniaturization in these MIR tunable lasers, most MIR-OPOs have been pumped at the wavelength of 2-3 µm generated with another OPO pumped by a Nd:YAG laser at the wavelength of 1.064 µm [11][12][13][14][15]. Since such tandem OPO configurations complicate equipments and their overall efficiencies are low, MIR-OPOs pumped by a laser with the wavelength of 2-3 µm directly generated by lamp-pumped Ho:YLF, Er,Cr,Tm:YSGG, and Cr,Tm,Ho:YAG lasers have been reported [16][17][18][19].…”