3D Printing of Micrometer‐Sized Transparent Ceramics with On‐Demand Optical‐Gain Properties

• Published in: Advanced materials (Weinheim) 2020-07, Vol.32 (28), p.e2001675-n/a
• Main Authors: Cooperstein, Ido, Indukuri, S. R. K. Chaitanya, Bouketov, Alisa, Levy, Uriel, Magdassi, Shlomo
• Format: Article
• Language: English
• Subjects: 3-D printers; additive manufacturing; Aluminum; Ceramics; gain media; Heat resistance; Light sources; Low temperature; Luminous intensity; Materials science; Neodymium; Optical components; Optical properties; Photopolymerization; Pressure; Scanning transmission electron microscopy; Sol-gel processes; sol–gel processing; Thermal resistance; Three dimensional printing; transparent ceramics; Visible spectrum; Yttrium; Yttrium-aluminum garnet
• ISSN: 0935-9648; 1521-4095
• DOI: 10.1002/adma.202001675

Transparent ceramics are usually polycrystalline materials, which are wildly used in many optical applications, such as lasers. As of today, the fabrication of transparent ceramic structures is still limited to conventional fabrication methods, which do not enable the formation of complex structures. A new approach for 3D printing of micrometer‐size, transparent ceramic structures is presented. By using a solution of metal salts that can undergo a sol–gel process and photopolymerization by two‐photon printing, micrometer‐sized yttrium aluminum garnet (YAG) structures doped with neodymium (Nd) are fabricated. The resulting structures are not only transparent in the visible spectrum but can also emit light at 1064 nm due to the doping with Nd. By using solution‐based precursors, without any particles, the sintering can be performed under air at ambient pressure and at a relatively low temperature, compared to conventional processes for YAG. The crystalline structure is imaged at atomic resolution by ultrahigh‐resolution scanning transmission electron microscopy (STEM), indicating that the doped Nd atoms are located at the yttrium positions. Such miniaturized structures can be used for diverse applications, e.g., optical components in high‐intensity laser systems, which require heat resistance, or as light sources in optical circuits. Yttrium aluminum garnet (YAG) is a transparent polycrystalline material, which is wildly used as a lasing medium when doped with rare‐earth metal. A new approach for 3D printing micrometer‐size, transparent YAG structures is presented, by using solutions without any particles and two‐photon polymerization printing. By doping the structures with Nd, they can emit light at 1064 nm, making them suitable for microlasers and optical circuits.