Fig. 1. ZGP single crystals grown by freezing method with ultralow gradient and ZGP OPO devices. (a) Crystals grown by HGF; (b) crystals grown by VGF; (c) regular ZGP OPO devices; (d) large aperture ZGP OPO devices

Fig. 2. Absorption coefficient comparison of ZGP OPO devices prepared by different methods

Fig. 3. OPO laser properties of ZPG. (a) Mid-IR output power; (b) beam quality at laser output power of 107 W